Sleep-wake rhythm disturbance (jetlag)
Sleep pathology in adults
The daily sleep-wake cycle allows us to organize our behavior in time and internally synchronize the regulation of many biological processes such as the body temperature rhythm, the Cortisol rhythm, the growth hormone excretion rhythm, etc.
The endogenous oscillator that is considered to have the greatest involvement in the regulation of sleep-wake rhythms is the suprachiasmatic nucleus of the hypothalamus.
There is a close relationship between the correct functioning of the circadian system and the health status of individuals. Alterations in the structures of the circadian system lead to alterations in the manifestation of rhythms. Alterations may also occur due to loss of the system’s synchronization capacity, for example in blind people who cannot synchronize 24 hours a day. At the same time, external alterations in rhythms can produce disorders in individuals, as in the case of Jet-Lag or changes in work shifts.
There are various pathologies related to the alteration of the circadian rhythm, among them the following stand out:
Advanced sleep phase syndrome
It is characterized by a forward shift of the sleep-wake cycle, with a tendency to sleep and wake up early. Patients often feel drowsy in the early afternoon and have difficulty staying awake at night.
Delayed sleep phase syndrome
It is characterized by a backward shift of the sleep-wake cycle, with a tendency to sleep and wake up late. Patients often have difficulty getting up early in the morning and falling asleep at night.
Sleep disorder due to shift work
Between 60%-70% of shift workers complain of sleep problems. Night workers sleep 5 to 7 hours less per week, reducing phase 2 and REM. They present a chronic state of sleep deprivation, due to the great influence of the circadian system on sleep, affecting the mood and performance of workers.
There is another characteristic associated with this disorder consisting of a substantial reduction in alertness during wakefulness. This has consequences fundamentally regarding their safety at work as well as in the personal sphere of their relationship with their family environment.
It occurs when traveling across different time zones, which can cause a temporal desynchronization between the internal circadian rhythm and the environment. This can cause daytime sleepiness, difficulty falling asleep, and nighttime awakenings.
Non-specific circadian rhythm disorders
These disorders are characterized by the presence of an alteration in the circadian rhythm that cannot be attributed to any of the previous pathologies. They can manifest with insomnia, daytime sleepiness, mood changes and alterations in appetite.
Irregular sleep-wake cycle pattern
It consists of the temporal disorganization and irregular behavior of the sleep-wake cycle.
Normally the number of hours slept during a 24-hour period is usually normal for the age (7-8 hours) but the moment in which sleep begins is totally anarchic. They never sleep in the same period of time. There is a total absence of an ultradian or circadian pattern at the onset of sleep.
The most widespread complaint consists of difficulty initiating or maintaining sleep during the night and the need to take frequent naps during the day. Sleep usually appears in three or four blocks of 2-3 hours duration in a 24-hour period, with marked variability in the time of falling asleep or waking up, if we compare between different days.
This alteration is rare in healthy patients, but is very often observed in people with congenital mental retardation, degenerative brain dysfunction, and dementia. It is usually chronic and there is no known effective treatment. Hypnotics are of little use.
Treatments to regulate the circadian rhythm use synchronizing agents such as Melatonin treatment, along with light stimulation (luminotherapy), manipulation of sleep schedules (chronotherapy), or physical activity. All of this is planned, depending on the case, to get the circadian rhythm back on track.