Daytime sleepiness: is there cause for concern?

If a person is chronically sleep deprived, that is, the duration of nighttime sleep is less than seven hours per day, and this continues day after day for a month or more, then daytime sleepiness is a logical consequence of the violation of the physiological norm of nighttime rest of the central nervous system and the whole organism.

But often, the desire to sleep during the day, especially after midday, which is difficult to overcome, arises in those who sleep enough at night. What is the reason for this?

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Causes of Daytime Sleepiness

So, the simplest reason for daytime sleepiness is constant lack of sleep, and obviously there are no questions about it. Although, as is known, the physiologically determined individual need for sleep may not coincide with generally accepted standards and be less or more than seven to eight hours. As a rule, this is due to the specifics of anabolism - when a little more time is needed for the biochemical processes of synthesis of substances and restoration of immunity (due to the production of T-lymphocytes) that occur at night.

This also includes a disruption of the circadian rhythm of sleep, that is, a shift in periods of wakefulness and sleep relative to the time of day, for example, during shift work, as well as in the case of a sharp change in time zone (jet lag syndrome).

In modern somnology (a field of medicine that studies the physiology and pathology of sleep), the following causes of daytime sleepiness are considered:

• insomnia (sleeplessness), the development of which can be caused by neurotic conditions, stress, mental disorders, etc.;
• brain pathologies (tumors, hematomas, cysts, hydrocephalus) and traumatic brain injuries;
• sleep apnea syndrome (impaired respiratory function during sleep of a mechanical or psychogenic nature);
• hypersomnia (psychophysiological, narcoleptic, iatrogenic, idiopathic);
• long-term latent depression;
• endocrine diseases (diabetes mellitus type II, hypothyroidism);
• lack of iron in the blood ( iron deficiency anemia ).

Daytime sleepiness is a dangerous symptom of sleep apnea ('lack of breath'), which is a short-term (15-25 seconds) sudden cessation of breathing caused by the cessation of contractions of the respiratory muscles. In this case, the normal structure of sleep is disrupted: a person either wakes up or his sleep becomes superficial. And when apnea is caused by a narrowing of the lumen of the airways during sleep, the diagnosis sounds like obstructive apnea syndrome. For this reason, some men with severe obesity after forty years of age cannot take deep breaths and speed up the rate of breathing, which gives grounds to diagnose them with such a pathology as alveolar hypoventilation of the lungs (the so-called Pickwickian syndrome), which is characterized by increased daytime sleepiness.

Speaking of hypersomnia, specialists mean excessive duration of sleep at night, as well as peculiar attacks of daytime sleepiness. First of all, this includes narcolepsy (Gelineau's disease), which is characterized by restless, often interrupted nighttime sleep and short-term drowsiness during the day - sometimes in the most unexpected situations, for example, when moving. In such cases, neurologists note cataplexy - muscle weakness (a kind of numbness) lasting a few seconds without loss of consciousness. The development of narcolepsy is associated with a genetically determined deficiency of the neuropeptide orexin (hypocretin), which is synthesized by the hypothalamus and ensures the transmission of excitatory nerve impulses.

Non-insulin-dependent diabetes mellitus is included in the list of causes of daytime sleepiness due to disturbances in the supply of glucose to the body's cells, which occurs when they are insensitive to insulin. It is also known that with this disease, the pineal gland (the pineal gland of the diencephalon) produces less melatonin - a neurohormone that regulates the body's circadian rhythms and is synthesized only at night. So any shifts in its production lead to sleep disorders in the form of insomnia or increased sleepiness during daylight hours.

With congenital or acquired hypothyroidism (insufficient level of thyroid hormones) - in addition to weakness, rapid physical fatigue, headaches, chilliness, dry skin - a person also suffers from increased daytime sleepiness. Almost the same symptoms occur with iron deficiency anemia.

Finally, drowsiness may be a side effect of taking decongestant, antihypertensive, antiasthmatic or steroid medications.

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How to combat daytime sleepiness?

Among the recommendations on how to combat daytime sleepiness, drinks containing caffeine are in first place. Caffeine has psychostimulating properties that help activate all body functions, including vascular tone and the synthesis of neurohormones. But doctors warn about the harm of overindulging in coffee and strong tea (particularly in the evening) for good reason, since excess caffeine can cause psychogenic addiction - theism, which is accompanied by headaches, nervousness, increased heart rate and, of course, insomnia. So drinking coffee after 4-5 p.m. is undesirable.

Morning exercises, a warm shower (or at least washing up to the waist) and breakfast are the three pillars on which a cheerful state is based throughout the working day. The water temperature can be gradually reduced to +28-30°C and contrast water procedures can be done.

For breakfast, it is useful to eat cereals, that is, porridge, vegetable salads with boiled meat or fish, as well as eggs and cottage cheese with sour cream.

Prevention of daytime sleepiness is proper preparation for nighttime sleep or sleep hygiene. According to the recommendations of specialists from the American National Sleep Foundation (NSF), it is necessary to adhere to healthy habits, namely:

• avoid eating late (after 7 p.m.);
• try to go to bed and wake up at the same time (even on weekends);
• take a calming shower every evening (with water temperature no higher than +40°C).
• in the evening, do not turn on too bright lights or too loud music in the apartment;
• If you have problems with night sleep, you should avoid daytime sleep;
• do physical exercise every day;
• the bedroom should be quiet, fresh and comfortable;
• Quiet activities before bedtime exclude the use of electronic devices (such as a laptop), since a certain type of light emitted from the screens of these devices activates the brain.

It is quite obvious that the prognosis of daytime sleepiness depends entirely on its cause. Thus, with obstructive sleep apnea syndrome, cerebral hypoxia and heart failure, up to cardiac ischemia, often occur. Although any daytime sleepiness - regardless of the etiology - negatively affects the general condition and performance of a person.

Diagnosis of daytime sleepiness

Diagnosis of daytime sleepiness is aimed at identifying the causes of this condition. Sometimes it is enough for a doctor to simply listen to the patient's complaints and clarify his daily routine and living conditions, as well as asking about past illnesses, injuries, stresses and medications used.

However, this is not always enough to make a diagnosis, and then a neurologist or somnologist conducts special testing to determine the optimal duration of nighttime sleep that provides the patient with a feeling of vigor upon awakening.

In addition, key neurophysiological indicators of sleep are studied using polysomnography, and the characteristics of the functioning of individual structures of the brain are determined by conducting EEG (electroencephalography).

Because daytime sleepiness often raises suspicion of sleep apnea, it may be appropriate to perform respiratory or cardiorespiratory monitoring (study of breathing rhythm during nighttime sleep) and to determine the level of oxygen in the blood using pulse oximetry.

Naturally, if there are diseases of any organs or systems, primarily the endocrine system, which may be involved in daytime sleepiness, it is necessary to undergo a full examination by specialists in the relevant field, including blood and urine tests.

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