Disorders of the circadian rhythm

Disorders of the circadian rhythm of sleep develop during desynchronization between the inner “sleep-wakeful” cycle and the outer day-night cycle. As a rule, patients suffer from insomnia and / or PDS, which are resolved as the internal circadian rhythms self-rearrange. The diagnosis is established clinically. Treatment depends on the etiology of the disease.

In case of circadian rhythm disturbances, endogenous sleep-wake rhythms (biological clock) and the external light-dark cycle are shifted (desynchronized). The cause may be internal (for example, the syndrome of delayed onset of sleep phases or phase advance phase syndrome) or external (for example, shift work, change of time zones).

If external causes other than the circadian rhythms of the body are present, including temperature and secretion of hormones, synchronization with the light-dark cycle (external) and desynchronization of rhythms with each other (internal desynchronization) can occur; In addition to insomnia and excessive sleepiness, these changes can cause nausea, malaise, irritability and depression. The risk of cardiovascular and metabolic disorders may increase.
The most adverse repeated disturbances of the circadian rhythm (for example, due to frequent long-distance travel, rotation of work shifts), especially when the rhythms change in the counterclockwise direction.

Moving counterclockwise causes a phase shift in biological rhythms, in which the awakening and falling asleep precede (for example, when flying to the east, as well as when the working schedule is day-night through the evening). Symptoms are resolved within a few days or, in some patients (for example, elderly), within a few weeks or months; while there is a restructuring of rhythms. Since light is a powerful synchronizer of the circadian rhythm, exposure of a bright light (solar or artificial light with an intensity of 5000-10 000 lux) to the patient after the desired awakening and the use of glasses, followed by lighting the light to the desired sleep, accelerates adaptation to new conditions. Melatonin before bedtime may be helpful (Other sedatives).

Patients with circadian rhythm disorders often resort to alcohol, sleeping pills and stimulants. Disorders of the circadian rhythm of the following conditions:

• The time zone change syndrome, jet lag (jet lag when moving to another time zone)
• Sleep disturbance during shift work, shift work
• Disorders of the circadian rhythm of sleep, sleep phase disorder syndromes

Jitter syndrome, jet lag (jet lag failure when moving to a different time zone)

This syndrome is caused by rapid movement through two or more time zones. Traveling to the east (transfer of sleep to an earlier time) causes a more pronounced failure than moving to the west (transfer of sleep to a later time).
If possible, before the next trip, travelers are advised to gradually mix the “sleep-wakefulness” cycle in order to adapt it to the conditions of the place of the intended stay; After arriving at a new place, they should maximize the effect of daylight (especially in the morning) on ​​the acceptance of daylight and the effect of darkness before bedtime. In addition, short-acting hypnotics and / or stimulants can be used for a short period after arrival.
Sleep disturbance during shift work, shift work

The severity of the symptoms is proportional to the following

• Shift frequency during shift operation
• The intensity of each change
• Number of consecutive nights
• Duration of shifts
• The counterclockwise movement frequency (sleep advance)

Preferably fixed shift work (i.e., Work at night or in the evening); rotation of shifts should go “clockwise” (i.e., day – evening – night). However, even with fixed shift work, there are violations, because daytime noise and light degrade the quality of sleep, and workers often reduce the time allotted for sleep to participate in social or family events.

Phantom work (maximum light, for those working at night, artificial light) for the period of wakefulness, as well as creating the most comfortable conditions for sleep (if possible, a dark and quiet room). Wearing sunglasses in the morning at home while waiting for sleep is also helpful. You can use blackout masks on the eyes and devices to neutralize noise. Taking melatonin at bedtime can also be helpful. With sustained sleep disorders that adversely affect daily activities, reveal the reasonable use of short-acting hypnotics and stimulants.

Disorders of the circadian rhythm of sleep, sleep phase disorder syndromes

In these syndromes, the patient has a normal quality and overall duration of sleep in the 24-hour cycle of the circadian rhythm, but there is a desynchronization of the desired and necessary sleep time. In more rare cases, the cycle does not fit in 24 hours and patients wake up and fall asleep sooner or later every day. If it is possible to adhere to their natural cycle, then no symptoms are observed in the patients.

 – Syndrome of delayed onset of sleep phases: It is characterized by late onset of sleep and late awakening (for example, 3:00 am and 10:00 am). This syndrome is more common in adolescence. The need for an early rise to go to work or school is associated with increased daytime sleepiness, poor school performance and skipping morning classes. They can be distinguished from people who go to bed late because they cannot fall asleep earlier, even if they try. A slight delay in the time of falling asleep (less than 3 hours) is treated by a gradual earlier awakening, as well as by therapy with bright daylight; Melatonin can be taken 4-5 hours before the desired sleep. An alternative method is to gradually delay the time of sleep and waking up from 1 to 3 h / day until the correct time of sleep and wakefulness is achieved.

 – Advance sleep phase syndrome: Early falling asleep syndrome (early falling asleep and early awakening) is more common among the elderly. For correction, you can use the therapy of bright light in the evening.

 –  Syndrome of the non-24-hour cycle of sleep and wakefulness: It occurs much less frequently and is characterized by a free sleep / wake up mode. The length of the sleep – wake cycle remains unchanged, but goes beyond 24 hours, resulting in a daily delay of sleeping and waking up for 1–2 hours. This disorder is more common among blind people. Tasimelteon, a melatonin receptor agonist, can increase the duration of sleep at night and reduce the duration of daytime sleep in completely blind patients with this disorder. A dose of 20 mg is prescribed once a day at bedtime, at the same time every night.

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