At what time does body temperature rise? Causes of sudden changes in temperature and ways to reduce it
Temperature indicators are important for the human body, because they indicate the state of health. When they change, it is customary to talk about the development of some pathological process that requires immediate therapeutic measures. This raises the question, why does body temperature fluctuate?
In addition to night rest and wakefulness, changes in body temperature can be observed throughout the day. And this phenomenon is facilitated by several reasons:
- active physical activity;
- overheating;
- implementation of digestive function;
- overexcitation due to emotional shocks.
In all of the above situations, a healthy person’s temperature may rise to subfebrile levels. In this case, no treatment is needed, just calm down a little and relax.
The only exception may be the development of hyperthermia, which is accompanied by symptoms in the form of an uncomfortable feeling in the area of the heart muscle, the occurrence of painful sensations in the head, and the appearance of dyspeptic disorders. In this situation, a doctor’s consultation is required, since the cause of this condition may be allergic manifestations, dystonia, or disorders in the endocrine system.
Causes of fever in women
Very often the temperature fluctuates during pregnancy. This process is associated with changes in hormonal levels and a significant increase in progesterone. Temperature changes can range from 36 to 37.3 degrees. At the same time, the woman feels fine.
This phenomenon is usually observed in the first ten weeks of pregnancy, when the body is adjusting to a new job. But in some patients this temperature can be maintained until the end of pregnancy.
Sudden changes in temperature then pose a danger when elevated levels are characterized by other symptoms such as the appearance of rashes on the skin, a painful feeling in the abdomen, dysuric symptoms and catarrhal phenomena. This can affect not only the woman herself, but also the development of the fetus. This condition requires urgent examination by a doctor and the appointment of adequate treatment.
Sudden changes in temperature can be observed in a woman during the period of ovulation. Temperature indicators range from 36 to 37.3 degrees. In this case, the patient complains of other symptoms such as:
- irritability;
- weakness;
- painful feeling in the abdomen;
- increased appetite;
- swelling.
At the beginning of menstruation, these signs should disappear, and temperature readings should reach 36 degrees. This condition is considered normal and does not require the help of a doctor.
Some women experience changes in body temperature early in menopause. This process occurs as a result of changes in hormone levels. Often a woman during menopause experiences symptoms such as:
- tides of gift;
- increased sweating;
- increased pressure;
- disruptions in the functioning of the heart muscle.
Such a difference in temperature does not pose a danger to the body. But if there are other complaints, then it is necessary to find out the reason for what is happening. Perhaps the doctor will prescribe hormone replacement treatment.
Development of thermoneurosis
If a patient’s temperature fluctuates, then he may have developed thermoneurosis. In such cases, an increase in temperature indicators to 38 degrees is observed. Occurs after stressful situations and emotional shock.
A conclusion about the presence of this pathology can only be made if there are no other, more significant reasons. In some situations, the patient is given aspirin testing. That is, it is necessary to take an antipyretic drug at a high temperature and monitor the dynamics of the surges.
If the indicators drop to normal values and do not rise within forty minutes, then we can talk about the development of thermoneurosis. Then the patient will be prescribed restorative therapy.
Possible causes of temperature changes
There are other reasons when an adult’s body temperature jumps, such as:
- heart attacks;
- purulent and infectious processes;
- development of tumor formations;
- the occurrence of inflammatory processes;
- the appearance of an autoimmune condition;
- injury to joint or bone structures;
- manifestations of allergic reactions;
- development of endocrine disorders;
- the appearance of hypothalamic syndrome.
With abscess and tuberculosis, temperature jumps from 36 to 38 degrees are often observed. This phenomenon is inexplicable, but experts say that the body periodically perceives the infection as a foreign phenomenon.
When tuberculosis occurs, temperature fluctuations may vary by several degrees throughout the day. If we are talking about a severe form of the disease, then you can see a curve on the graph.
This phenomenon is also typical for purulent processes. Temperatures can rise to 38 degrees. After opening the infiltrate, the temperature returns to normal.
The temperature in the evening may increase in the presence of chronic processes in the form of:
- adnexitis;
- sinusitis;
- pharyngitis;
- pyelonephritis.
Hyperthermia in such situations is manifested by additional symptoms. Therefore, it requires therapeutic therapy. Antibacterial medications are prescribed, but only after a detailed examination.
If temperature fluctuations are caused by the appearance of a tumor-like formation, then the course of the disease and treatment will depend on its location. In most cases, surgery is performed, after which the indicators return to normal.
If there are disturbances in the functioning of the endocrine system, the patient may complain:
- for weight loss;
- to increased irritability;
- to sudden mood swings;
- for tachycardia;
- for interruptions in the heart muscle.
To establish an accurate diagnosis, the patient needs to undergo an examination, which includes:
- donating blood for general and biochemical analysis;
- urine delivery;
- performing ultrasound diagnostics;
- performing electrocardiography;
- blood donation for the amount of hormones.
After this, a treatment regimen is prescribed.
Ways to reduce temperature
Before starting the treatment process, you need to identify the cause. When the diagnosis is confirmed, you can begin prescribing medications.
The treatment regimen may consist of:
- from antibacterial drugs;
- from antiviral agents;
- from anti-inflammatory medications;
- from antihistamines;
- from hormone therapy;
- from antipyretic drugs.
Raising temperature indicators acts as a protective reaction of the body. But in some cases, a temperature of 37 degrees is not noticed by a person, and therefore the inflammatory process can proceed for quite a long time. As they say in medicine, this phenomenon indicates a sluggish process.
Antipyretic medications should be taken only at temperatures above 38 degrees. Until this moment, the body independently fights the pathological phenomenon.
After treatment has been completed, the patient needs to focus all his efforts on strengthening immune function. To do this you need:
- lead a healthy lifestyle;
- play sports and carry out hardening procedures;
- follow the diet. It must be balanced and correct. You should completely avoid alcoholic and carbonated drinks. You should also exclude fast food, processed foods, fatty, fried and spicy foods;
- observe the drinking regime. This will remove pathogenic microorganisms and prevent dehydration. A person should drink at least two liters of liquid per day;
- take vitamin supplements and eat foods that are rich in vitamins and minerals. The diet should include fresh vegetables, fruits and berries.
A difference in temperature indicators can indicate both a physiological and an abnormal process. To protect yourself, you need to see a doctor, undergo an examination and exclude many factors.
If the temperature of 37 degrees is maintained for 24 hours and then drops, then there may have been overwork or emotional shock. This phenomenon often occurs in childhood.
What are the reasons for a constant or periodic slight increase in temperature at certain times of the day, in the evening or during the day? Why is an increase in body temperature from 37.2 to 37.6° often observed in children, the elderly or pregnant women?
What does low-grade fever mean?
Low-grade fever is indicated slight increase in body temperature before 37.2-37.6°C, the value of which, as a rule, fluctuates in the range of 36.8 ± 0.4 °C. Sometimes temperatures can reach 38°C, but do not exceed this value, since a temperature over 38°C indicates fever.
Low-grade fever can affect anyone, but children and elderly people most vulnerable because they are more susceptible to infections and their immune system is unable to protect the body.
When and how does low-grade fever appear?
Low-grade fever may appear in different moments of the day, which sometimes correlates with possible pathological or non-pathological causes.
Depending on the time at which low-grade fever occurs, we can distinguish:
- Morning: The subject suffers from low-grade fever in the morning when the temperature rises above 37.2°C. Although in the morning physiologically normal body temperature should be below the daily average, therefore even a slight increase can be defined as low-grade fever.
- After meals: After lunch, due to digestive processes and related physiological processes, body temperature rises. This is not uncommon, so a low-grade fever is considered to be an increase in temperature of more than 37.5°C.
- Day/evening: During the day and evening there are also periods of physiological increase in body temperature. Therefore, subfebrile temperature includes an increase above 37.5°C.
Low-grade fever may also occur various modes, which, as in the previous case, depends on the nature of the reasons, for example:
- Sporadic: This type of low-grade fever is episodic, may be associated with seasonal changes or the onset of the menstrual cycle in women of childbearing age, or may be a consequence of intense physical activity. This form causes the least concern, since, in most cases, it is not associated with pathology.
- Intermittent: This low-grade fever is characterized by fluctuations or periodic occurrence at certain points in time. May be associated, for example, with physiological events, periods of intense stress, or an indicator of disease progression.
- Persistent: A constant low-grade fever that persists and does not subside throughout the day and lasts for quite a long time is alarming, as it is closely associated with certain diseases.
Symptoms associated with low-grade fever
Low-grade fever can be completely asymptomatic or accompanied by a wide variety of symptoms, which, as a rule, become the reason for visiting a doctor for diagnosis.
Symptoms most often associated with low-grade fever include:
- Asthenia: The subject experiences a feeling of fatigue and exhaustion that directly correlates with the rise in temperature. This may be due to infections, malignancies and seasonal changes.
- Pain: Along with the onset of a low-grade fever, the subject may experience joint pain, back pain, or leg pain. In this case, there may be a connection with the flu or a sharp seasonal change.
- Cold symptoms: if a headache, dry cough and sore throat appear along with a low-grade fever, then hypothermia and exposure to the virus may be occurring.
- Abdominal symptoms: along with a slight increase in temperature, the patient may complain of abdominal pain, diarrhea, and nausea. One of the possible reasons is infection with a gastroenterological infection.
- Psychogenic symptoms: Sometimes it is possible, along with the appearance of low-grade fever, the appearance of episodes of anxiety, tachycardia and sudden trembling. In this case, it is possible that the subject is suffering from depressive problems.
- Enlarged lymph nodes: if a low-grade fever is accompanied by swollen lymph nodes and profuse sweating, especially at night, it may be associated with a tumor or infection, for example, mononucleosis.
Causes of low-grade fever
When low-grade fever is sporadic or periodic, has a correlation with certain periods of years, months or days, then it is almost certainly associated with a non-pathological cause.
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Causes of temperature...
Prolonged and persistent low-grade fever, which persists for many days and appears mainly in the evening or during the day, is often associated with a specific disease.
Causes of low-grade fever, without pathology:
- Digestion: After eating food, digestive processes cause a physiological increase in body temperature. This may cause a mild low-grade fever, especially if you have ingested hot food or drinks.
- Heat: In summer, when the air reaches high temperatures, being in a room that is too hot can cause increase in body temperature. This happens especially often in children and newborns, whose body thermoregulation system is not yet fully developed.
- Stress: In some individuals, especially those who are sensitive to stressful events, a low-grade fever may be interpreted as a reaction to stress. Typically, a rise in temperature occurs in anticipation of stressful events or immediately after they occur. This type of low-grade fever can occur even in infants, for example when crying very intensely for a long time.
- Hormonal changes: In women, low-grade fever may be closely related to hormonal changes. Thus, in the premenstrual stage, body temperature increases by 0.5-0.6°C, and this can determine a slight increase in temperature in the range from 37 to 37.4°C. Also, in the early stages of pregnancy, hormonal changes lead to a similar increase in body temperature.
- Season change: as part of the change of season and a sharp transition from high temperatures to cold, and vice versa, a change in body temperature may occur (without a pathological basis).
- Medicines: Some medications have low-grade fever as a side effect. These include antibacterial drugs of the beta-lactam class of antibiotics, most anticancer drugs and other drugs such as quinidine, phenytoin and some vaccine components.
Pathological causes of low-grade fever
The most common pathological causes of low-grade fever are:
- Neoplasms: Tumors are the main cause of persistent low-grade fever, especially in older people. Among the tumors that most often lead to an increase in body temperature are leukemia, Hodgkin lymphoma and several other types of cancer. Typically, low-grade fever in the case of a tumor is accompanied by rapid weight loss, a strong feeling of fatigue, and in the case of tumors involving blood cells, anemia.
- Viral infections: One of the viral infections that causes low-grade fever is HIV, which leads to the development of acquired immunodeficiency syndrome. This virus tends to destroy the subject's immune system, therefore causing exhaustion, which is manifested by many symptoms, one of which is low-grade fever, opportunistic infections, asthenia and weight loss. Another viral infection that causes persistent low-grade fever is infectious mononucleosis, known as “kissing disease” due to its transmission by salivary secretions.
- Respiratory tract infections: Low-grade fever is often present in cases of infection involving the respiratory tract (such as pharyngitis, sinusitis, pneumonia, bronchitis or a cold). One of the most dangerous respiratory tract infections that causes low-grade fever is tuberculosis, which is accompanied by profuse sweating, asthenia, weakness and weight loss.
- Thyroid problems: Low-grade fever is one of the symptoms of hyperthyroidism, caused by thyrotoxic destruction of the thyroid gland. This destruction of the thyroid gland is called thyroiditis and is often caused by a viral infection.
- Other pathologies: There are other diseases, such as celiac disease or rheumatic fever caused by streptococcal infection, beta-hemolytic type, which include the appearance of low-grade fever. However, in these cases, low-grade fever is not the main symptom.
How is low-grade fever treated?
Low-grade fever is not a pathology, but a symptom with which the body can indicate that something is going wrong. In fact, there are many diseases that can lead to persistent low-grade fever.
However, often slight increase in body temperature has no pathological causes and can be compensated using simple natural remedies.
Finding the cause of low-grade fever is difficult, but, in any case, you should consult a doctor.
Natural remedies against non-pathological low-grade fever
To combat the symptoms caused by low-grade fever, you can use natural remedies, such as herbal medicine. Of course, you should consult your doctor before resorting to one of these remedies.
Among medicinal plants, used in case of low-grade fever, the most important are:
- Gentian: Used in cases of intermittent low-grade fever, this plant contains bitter glycosides and alkaloids, which gives it antipyretic properties.
Used as a decoction: 2 g of gentian roots are boiled in 100 ml of boiling water, left to infuse for about a quarter of an hour, and then filtered. It is recommended to drink two cups per day.
- White willow: Contains, among other active substances, salicylic acid derivatives, which have the same antipyretic effect as aspirin.
A decoction can be prepared by bringing a liter of water containing about 25 grams of white willow root to a boil. Boil for about 10-15 minutes, then filter and drink two to three times a day.
- Linden: Useful as an associated antipyretic, linden contains tannins and mucilages.
by Notes of the Wild MistressUsed in the form of infusions, which are prepared by adding a tablespoon of linden flowers to 250 ml of boiling water, followed by infusion for ten minutes and filtering, you can drink several times a day.
It would seem that there is no doubt - the normal temperature is 36.6° Celsius. This is what we have been doing since early childhood. But is this really so?
How does body temperature change depending on various factors?
It turns out that scientists have long been engaged in experiments on measuring the temperature of the human body in various situations. And it turned out that 36.6° Celsius is an extremely unstable value. But in fact, temperature varies greatly depending on factors such as environmental conditions, human activity at one time or another, eating, sleeping or waking, and even emotions or the area of the body where the measurement is taken.
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So, if the air in the room is heated to approximately 20°, then when measuring you can see that on the thigh muscle the temperature will be 35°, on the calf muscle - 33°, and in the center of the foot - only 27-28°. Under the same measurement conditions, you can see that the temperature in the rectum will be 37°, and in the liver - 38°. And even in the brain, temperature fluctuations of 1° or more occur.
In addition, women's temperature changes during the menstrual cycle depending on the level of sex hormones. And it should be noted that in all people, without exception, the temperature may rise by 1-2°C during intense physical work.
How does body temperature depend on age?
Body temperature in children can be very unstable. It changes towards an increase during crying or screaming, as well as during active games in the fresh air or while eating.
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But in older people, the normal temperature can drop to 35°. This is due to the fact that with aging, metabolism slows down, so the body begins to adjust to a lower temperature level.
Scientists have found that in the place where temperature is usually measured - the armpit - the temperature changes by a whole degree during the day. In this case, the temperature maximum occurs at 4-6 o'clock in the evening, and the minimum - at 3-4 o'clock in the morning. This condition is called the circadian rhythm of the body's biological clock.
What to do when the temperature rises
Usually, noticing an increase in temperature, we begin to worry whether it is caused by some kind of disease and try to take all possible measures to reduce it. It should be noted that an increase in temperature indicates a natural protective reaction of the body in the event of the introduction of any infection that irritates the brain centers responsible for thermoregulation.
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An increase in body temperature is much worse for microbes than for humans, so you should not abuse antipyretics. They should be used at temperatures above 38.5-39°, as well as in case of individual intolerance to high temperature or severe intoxication of the body with vomiting, which can lead to dehydration.
First of all, it is necessary to arrange for a person with a high temperature to drink plenty of fluids. A large amount of fluid entering the body increases sweating and eliminates toxins in the urine, thereby reducing the temperature.
But if the temperature has already risen above 39°, you should use antipyretics.
It is important to identify the correct cause of high fever, and only a doctor can help you with this!
Daily human temperature curve
If you measure body temperature in different places, different values can be obtained as a result of unequal heat transfer conditions. So, for example, when measuring the temperature in the rectum, the figures obtained are 0.4 - 0.5° higher than the values that are determined when measuring in the armpit. The temperature of the skin surface is even lower. So, at a temperature in the armpit of 36.6°, the temperature of the facial skin is 20 - 25°, the limbs are 25°, and the abdominal skin is 34°. Therefore, true body temperature is best characterized by figures obtained by placing a thermometer in the armpit, when the shoulder is pressed against the body, or even more accurately when measured in the mouth or rectum.
Temperature changes during the day
By measuring body temperature at certain intervals, it is possible to construct a curve based on the data obtained that characterizes temperature measurements throughout the day.
With the typical human lifestyle, the daily curve is characterized by regular fluctuations. The lowest temperature is around 4 - 6 hours, the highest - around 16 - 18 hours.
The characteristic course of changes in body temperature during the day is determined by those changes in metabolism that are associated with food intake, the active state of the body, etc. By comparing the curve depicting daily temperature fluctuations with daily curves of changes in motor activity, respiratory rate, active urine reaction, etc. etc., one can verify the parallel course of these curves.
By changing the lifestyle, the curve can be distorted. Similar experiments were carried out on people who slept during the day and were awake at night. At the same time, it was possible to obtain temperature curves with a maximum at 6–9 a.m. and a minimum at 6 p.m. These experiments show that the features of the temperature curve are determined by influences coming from the cerebral cortex.
In addition to these daily fluctuations, temperature can vary significantly depending on the metabolic changes that accompany muscle activity. After significant physical exertion, body temperature rises from a few tenths of degrees to 2° and even in some cases up to 3°.
Temperature of young children
The temperature of young children is especially unstable, which is explained by the insufficiency of mechanisms regulating the relationship between heat production and heat transfer. These mechanisms represent a relatively new acquisition in vertebrate evolution; they develop late in the process of ontogenesis. A number of representatives of higher vertebrates are born with a lack of thermoregulation, representing initially poikilothermic animals. Something similar occurs in the human fetus, especially when it is born prematurely. This circumstance forces us to take a number of protective measures against hypothermia or overheating of the body of newborns.
Without respect and consideration of biorhythms, progress and improvement in health are impossible
Real health is a properly organized lifestyle. Without respect and consideration of biorhythms, progress and improvement in health are impossible.
Human nature is complex, and we have not one, but several pacemakers, which may or may not be synchronized (desynchrosis). I want to tell you about one important pacemaker – temperature.
This is important to know, since the rhythmic organization of basic physiological functions (sleep, nutrition, physical activity, stress) affects the health, performance and resistance of the body to various influences.
Adaptation of the human body to changing environmental conditions (changes in time of day, seasons, solar activity, etc.) is carried out using biological rhythms, or “internal clocks”.
Formed during evolution, the circadian rhythms of organisms are synchronized with the duration of photoperiods. Being one of the fundamental properties of living matter, biorhythms are manifested in the functioning of all body systems (nervous, endocrine, reproductive, cardiovascular, etc.). Biorhythms are divided into circadian (daily), circannual (annual), ultradian (lasting more than a day), infradian (lasting less than a day), etc. The hypothalamus is considered the center for regulating biorhythms. The circadian rhythm generator is localized in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The suprachiasmatic nuclei receive information about illumination through the retinohypothalamic tract. The circadian pacemaker responds to various parameters of illumination - wavelength, duration and exposure time. The main external synchronizer of circadian rhythmicity is the light-dark cycle, but even in the absence of external light (solar) influences (bunker, submarine, cave, etc.) circadian rhythms are preserved, changing in duration, due to internal periodicity.
Moreover, melatonin, due to its hypothermic properties, has a direct effect on the circadian rhythm of body temperature. Although the suprachiasmatic nuclei (which are driven by light) clearly play a critical role in regulating circadian timing systems, there is evidence for the existence of other pacemakers in mammals as well. For example, in Saimiri monkeys with damaged suprachiasmatic nuclei, the rhythms of eating, drinking and activity disappear,but the daily cycle of body temperature remains unchanged.
The fact that subjects exhibit spontaneous desynchronization, i.e. the discrepancy between the circadian rhythm of body temperature and the sleep-wake cycle indicates the existence of at least two drivers. There are certain sets of rhythms that are never desynchronized in such experiments and, therefore, must be subordinated to a common pacemaker. One such set includes the rhythms of sleep and wakefulness, skin temperature, concentration of growth hormone in the blood and calcium in the urine. It is assumed (although this is by no means proven) that this group of rhythms is controlled by the suprachiasmatic nuclei. The second group of indicators, which vary consistently even when desynchronization of other body functions occurs, includes REM sleep cycles, core body temperature, blood cortisol levels and urine potassium levels.
The pacemaker that controls these rhythms is apparently more stable than the one that controls the rhythm of sleep and wakefulness. In cases where the rhythms became free-flowing, that is, in the absence of external time-setters, this group rarely deviated. The temperature regime is adjusted during flights much later than the light conditions. Even if a person is completely cut off from any external signals, such as daylight hours, weather changes, eating hours and others, he will still have daily temperature fluctuations
. However, in such a situation, the oscillations remain rhythmic, but their cycle is not exactly 24 hours. Rhythmic fluctuations in body temperature under conditions of isolation from external factors usually occur within 24–25 hours, and this period of time is called circadian periodicity. That is, all daily temperature fluctuations are entirely based on endogenous biological rhythms, which are synchronized with the period of the Earth’s rotation around its axis. If a person moves in space with the intersection of hour meridians, then after arriving at a permanent place of residence for 1 - 2 weeks, his daily fluctuations in body temperature will be synchronized with the new local time (!).
Body temperature Body temperature is a complex indicator of the thermal state of the body of animals, including humans. Our body temperature is easily measured and is a very useful indicator. The problem now is that the fluctuations are minimized, which leads to many failures. We are in the same temperature comfort zone day and night in all seasons of the year and this is not very good. Very often the temperature rhythm begins to conflict with the light rhythm and this leads to desynchronization, which is the cause of many problems.
So let's understand how the temperature cycle works. The main thing, as always, is the hypothalamus. The endocrine glands are involved in the hypothalamic regulation of body temperature, mainly the thyroid and adrenal glands. The thyroid gland and its hormones increase thermogenesis and increase metabolism, raising temperature. The adrenal glands produce adrenaline, which also enhances oxidative processes in tissues, particularly in muscles, increases heat generation and constricts skin vessels, reducing heat transfer.
The nerve cells of the hypothalamus have receptors that directly respond to body temperature by increasing or decreasing the secretion of TSH (thyroid-stimulating hormone), which, in turn, regulates the activity of the thyroid gland, the hormones of which (T3 and T4) are responsible for the intensity of metabolism. To a lesser extent, the hormone estradiol is involved in temperature regulation (it plays a major role in the thermoregulation of women’s bodies during the menstrual cycle); an increase in its level leads to a decrease in basal temperature.
Circadian rhythms occupy a leading place among human biological rhythms. Modern authors call their totality and consistency - temporary organization, emphasizing that it plays a special role, both in the synchronization of intraorganismal processes and in the interaction of the organism with the environment. Among the parameters of rhythm, mesor and amplitude occupy a special place. The mesor (average daily level) reflects the central line around which fluctuations in physiological function occur throughout the day. Amplitude (range of oscillations) is the most plastic indicator of functional morphology and one of the first to change under the influence of various factors. The magnitude of the amplitude can serve as an indicator of the adaptation process.
The “thermostat” (hypothalamus) is located in the brain and is constantly engaged in thermoregulation. During the day, a person’s body temperature fluctuates, which is a reflection of circadian rhythms. Each person's body temperature fluctuates slightly throughout the day, remaining in the range of 35.5 to 37.0°C for a healthy person. Following the circadian rhythm, the lowest body temperature is observed in the morning, around 6 o'clock, and the maximum value is reached in the evening. Like many other biorhythms, temperature follows the sun's daily cycle , not our level of activity.
People who work at night and sleep during the day exhibit the same temperature cycle as others.
Temperature cycle
1. Morning and awakening. Experiments by American physiologists, conducted under the guidance of Professor Zeisler, showed that sleep and awakening are closely related to body temperature. In the morning, body temperature rises. Scientists have found that among hunter-gatherers, sleep and wakefulness patterns correlate not only with the daily and night routine (which is trivial and does not need confirmation), but also with the surrounding temperature. The last conclusion is less obvious, but is confirmed by measurements. Awakening among both the San and the Tsimans occurs when the ambient temperature is minimal
. Awakening is indicated by a sharp decrease in the temperature of the fingers, reflecting the constriction of peripheral vessels, which is accompanied by an increase in blood flow to the brain, and therefore indicates the transition from sleep to wakefulness. Among the San, the minimum temperature occurs an hour after dawn, and among the Tsimans, an hour before dawn. The time for both of them to fall asleep occurs during a sharp drop in ambient temperature, and not at the onset of darkness. This explains the slightly different daily routines in these largely similar traditional societies. Probably, shifting sleep to the coldest time of day helps to save energy costs, and is therefore more acceptable for living in traditional conditions. Exercise and moderate physical activity in the morning contribute to a rise in body temperature and higher activity. I am also a proponent of a protein-rich breakfast, as protein has the highest thermogenic effect compared to other nutrients. Thus, a person always wakes up at the rise of the temperature curve. Therefore, the duration of sleep depends on which phase of the temperature cycle the moment of falling asleep occurs:
another rise in body temperature will wake you up, even if you haven’t slept for several days before.
As for our activity, mental and physical activity increases as body temperature rises. Physical activity helps keep you mentally alert throughout the day. Thus, athletes know that “warming up” increases performance, and, indeed, optimal levels of hyperthermia (body core T = 38.7 - 39.2°) ensure maximum performance in exercises for strength, speed, flexibility and agility. And when performing intermittent physical activity, an increase in body temperature to the level of 38.7-39.2 ° C is “normal” and even desirable for the efficiency of muscle work. If a person experiences intense physical activity, then the optimal temperature will be elevated (for strength training). Body temperature reaches a maximum in the evening, decreases at night and rises quickly upon awakening.
Research also shows that changes in normal body temperature caused by heat or cold can have a significant impact not only on mood, but also on cognitive function. Cognition is the process that governs how we respond to our environment, as well as our ability to store memories and perform mental tasks such as arithmetic. And this ability worsens if body temperature deviates from normal. Extreme temperatures or prolonged exposure to uncomfortable weather can change body temperature, disrupting homeostatic control (the body's ability to maintain its temperature). Research has also shown that when the ambient temperature drops, body temperature drops and this negatively affects cognitive abilities. Scientists from the University of Kent (USA) placed subjects in water at a temperature of 13 degrees Celsius for 30 minutes. After this, most people's body temperature dropped to 35-36 degrees Celsius, just below the normal range of 36.5-37.2 degrees Celsius. Participants rested for 15 minutes, and then the researchers asked them to complete the Stroop Test (the name of the color is written in the box, but on the answer form you must indicate the color of the font in which the word is written). Despite its apparent simplicity, the test requires some cognitive effort. Participants were asked to name the color of the font as quickly as possible. It turned out that the test was significantly more difficult for participants placed in cold water. This study shows that low body temperature has a significant effect on attention to detail, which is considered a marker of cognition.
Reduced body temperature during the day is a common symptom of hypothyroidism. A regular drop in temperature is one of the first signs of thyroid dysfunction. Subclinical hypothyroidism is often accompanied by chronic fatigue, low temperature, weight gain, and weakness. Normal axillary body temperature, determined immediately after waking up in the morning to diagnose hypothyroidism, is in the range of 97.4 - 98.2 degrees Fahrenheit (36.3 - 36.8 ˚C). Women should measure their body temperature during the first 5 days of their cycle and then average the readings. A temperature below 36.3˚C indicates insufficient thyroid function (hypothyroidism). If the average temperature was calculated using the method described above and it turns out to be below 36.5 °C, then you have a very high probability of hypothyroidism. The question is whether this disorder is a primary insufficiency of the thyroid gland or whether it refers to a “problem” in the pituitary gland or adrenal insufficiency.
3. Evening and falling asleep
At 18-19 hours the maximum body temperature is observed, after which it begins to decrease. It’s good if going to bed coincides with a lower body temperature. The individual biorhythm of the time of rapid decline in temperature (extreme inflection point on the curve) corresponds to the optimal time for falling asleep. This way, you can fall asleep easily and get enough sleep faster. Therefore, all procedures associated with cooling the body improve falling asleep. Light is also important; low yellow light promotes the production of melatonin, which causes sleepiness and controls body temperature.
We have already said that during the day, body temperature experiences cyclic fluctuations with an amplitude of about 1 °C. People tend to fall asleep when their body temperature drops and wake up when their body temperature rises. 19:00 - the highest level of blood pressure and the highest body temperature. The internal signal for going to sleep is a decrease in body temperature.
Our body releases heat through our arms, face and legs when it's time to sleep. Cooling continues until approximately four in the morning. However, if something interferes with the decrease in body temperature, the quality of sleep immediately deteriorates. A person cannot fall asleep and suffers from insomnia. In connection with this, the scientist advises choosing bed linen wisely, giving preference to natural fabrics. A mattress made of foam or other synthetic materials requires a mattress pad made of natural wool. And those who have problems falling asleep can even keep the pillow in the refrigerator during the day. You can also run your hands under cold water for a few minutes before going to bed. After this, it is recommended to go to bed immediately.
However, many people fall asleep soundly after a warm bath, and this effect is well known to doctors. Perhaps the fact is that heating leads to the expansion of the vessels of the arms and legs, which are effective heat exchangers. When a person leaves the bath, the dilated vessels of his limbs intensely give off heat and cool the body.
There is another explanation. In kangaroo rats, local heating of the hypothalamic region increases the duration of slow-wave sleep. Perhaps the fact is that the overheated hypothalamus turns on an additional brain cooling system. If this mechanism is also true for humans and the blood passing through the vertebral arteries from the heated body to the brain predominantly enters the hypothalamus region, the same thing happens to it as in the marsupial rat: The hypothalamus turns on the cooling system, which causes sleep, more precisely, its slow-wave phase.
An interesting description of the yawning mechanism from the point of view of brain cooling. So, relatively recently, scientists began to consider the act of yawning as a system for rapid cooling of the brain, which also made it possible to explain the connection between yawning and falling asleep and hypoxia. The dependence of the frequency of yawning on ambient temperature has been noted for a long time. In addition, the effect of yawning on temperature-dependent attacks of epilepsy, migraine and multiple sclerosis indicated an important role of this act in thermoregulation of the brain. The supposed connection between yawning and brain cooling was proven when in 2010, researchers inserted temperature sensors into the brains of rats and found that an increase in brain temperature of just 0.1°C instantly provoked bouts of yawning in the rodents, followed by a decrease in brain temperature of 0 .5°C. However, these observations could not be substantiated anatomically for a long time - how does yawning remove excess heat from the brain? The act of yawning begins with the opening of the mouth and expansion of the nasopharynx, which leads to its filling with cold air through the mouth opening. Try yawning. Did you feel a chill and a strong tension in the very center of your head?
It turned out that at the peak of yawning, the lower jaw tightens the pterygoid muscles, and they, in turn, retract the sphenoid process, dragging behind it the posterior wall of the maxillary maxillary sinus. The volume of the nasal sinuses in an adult reaches 34 cubic meters. cm, and the tension of the back walls during yawning increases their size by another third. The resulting negative pressure in the sinuses “sucks” cold air from the nasopharynx. This air causes the evaporation of moisture on the walls of the sinus, thereby cooling the capillaries of the mucous membrane. The blood cooled in this way is then collected in the veins of the pterygoid plexus. With the completion of a yawn, the jaw tightens and the masticatory muscles compress the pterygoid plexus (stage 4), causing cooled blood to flow into the dural sinuses. This blood, in turn, cools the cerebrospinal fluid, the flow of which also increases during yawning - in this act it acts as a coolant for the central nervous system. Thus, cooling of the brain will occur immediately after the completion of the act of yawning.
4. Night and recovery
Most people sleep better in a cool room. During sleep, the body cools down; at 4.00-5.00 the body temperature is at its lowest. The ideal temperature in the bedroom is 18–21 °C. In people with severe cases of insomnia, the daily rhythm of body temperature is disrupted: it varies slightly and without certain patterns. Or the rhythm exists, but its period is far from 24 hours. With this rhythm, a person manages to fall asleep normally only on days when the temperature drops in the evening hours.
Body (and brain) temperature follows a circadian rhythm, and when it drops, you want to sleep. In addition, lower night temperatures promote nighttime fat burning, autophagy, and growth hormone production. Cooling the brain is not just associated with falling asleep, but stimulates it. This is probably the basis of the well-known household method of combating insomnia: you need to freeze thoroughly. A group of American scientists from the University of Pittsburgh, located in Pennsylvania, managed to develop a technique that allows one to quite effectively get rid of insomnia. A special cap that cools the patient’s frontal cortex can significantly improve the quality and productivity of night’s rest. In the study discussed here, American experts led by Dr. Eric Nofzinger studied the effect of low temperature on the activity of areas of the cerebral cortex, as well as on metabolic processes in patients suffering from insomnia. In doing so, the scientists relied on data obtained from previous studies, according to which the activity of metabolic processes in the frontal cortex of a healthy person decreases during sleep. At the same time, it has been proven that in patients suffering from insomnia, the activity of this part of the brain remains increased during a night's rest.
For proper sleep, alternating slow and fast sleep, associated with alternating low and high temperatures, is very important.
Numerous experiments indicate that changes in brain temperature are not random. In rats, it always increases in response to external stimuli: pain, social contact with another individual, sexual arousal. Moreover, the temperature of each part of the brain, in response to different stimuli, rises to one specific value, as if it is tending towards it.
For example, for the nucleus accumbens of the rat brain this temperature is 38.5°C. And in the slow-wave sleep phase, cooling occurs by an amount ranging from a few tenths of a degree to several degrees in different parts of the brain in different animals. Obviously, brain temperature does not change passively, but regulates the activity of nervous tissue. It is not for nothing that a person who thinks soberly is said to have a cool head.
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