News & Views

Sleep, circadian rhythm and quarantine

By Zach Pearl, PhD Staff


This outbreak of Covid-19 pandemic affects us all and brings about high level of stress. Such period affects various aspects in our daily life including health, economic, social and cultural aspects. Being forced to stay at home, work from home, do homeschooling with children, drastically minimize outings and daylight exposure and reduce social interaction. These may have a major impact on daily functioning and nighttime sleep.

Living organisms, including humans, have an internal, biological clock that helps them anticipate and adapt to the dramatically different phases of the day and adjust their body and behaviour accordingly. This regular adaptation is referred to as the circadian rhythm 1 2 . Circadian rhythm or the “body clock” is a cycle lasting on average a bit more than 24 hours. The clock regulates critical body functions such as hormone levels, sleep, body temperature, immune functions, blood pressure, behavior, and metabolism. 1 2

Located in a region of the brain called the suprachiasmatic nucleus, this clock is controlled by various environmental signals, most importantly the light–dark cycle and melatonin – a hormone in charge of sleep regulation and the circadian clock. Melatonin is produced in the pineal gland when the eyes send signals to the biological clock that it is dark. Its levels rise in the evening and remain elevated throughout the night, promoting sleep. Upon exposure to light in the morning, the circadian clock delays melatonin release. 3

Because circadian rhythm is governed by daylight, the current Covid-19 quarantine situation is likely to negatively affect it.

Most people experience major changes in daily routines, high stress level insecurity about their health and low exposure to daylight. 4 The combination of these factors may lead to sleep difficulties as well as other health risks. 5

Short-term consequences of sleep deprivation include increased stress responsivity, somatic pain, reduced quality of life, emotional distress and mood disorders, and cognitive, memory, and performance deficits. Long-term consequences of sleep disruption in otherwise healthy individuals include hypertension, dyslipidemia, cardiovascular disease, weight-related issues, metabolic syndrome, type 2 diabetes mellitus, and colorectal cancer. As a result of the potential consequences of sleep disruption, health care professionals should be cognizant of how managing underlying medical conditions may help to optimize sleep continuity and consider prescribing interventions that minimize sleep disruption. 6

There are several treatment options designed to address the desynchronization, here are a few:

Behavioural therapy: Depending on the disorder, certain behavioural therapies such as maintaining regular sleep-wake times, avoiding naps, getting regular exercise, avoiding nicotine, caffeine, and stimulating activities within several hours before desired bedtime, may help alleviate the symptoms, but their effectiveness has not been proven over time.

Bright light therapy: Timed exposure to bright light (natural, artificial or a combination) can shift the sleep-wake cycle to earlier or later times, in order to correct the misalignment between the circadian system and the desired sleep-wake schedule. Several studies have established that the human circadian system is very sensitive to light, and that the efficacy of light in resetting circadian rhythms is determined by the dose, light wave, and time-of-day that the light is administered . 7 8

Medication: Medications usually either promote sleep, as done by hypnotic medications, or promote daytime wakefulness, as done by stimulants. Melatonin products were found to be effective in treating Circadian Rhythm Sleep Disorders. Melatonin administration in the evening has been shown to benefit patients with Delayed Sleep Phase Disorder (who only fall asleep late at night) by advancing circadian rhythms and sleep timing. 9 Melatonin has also been successful in treating biological clock misalignments (free-running) in blind patients5, shift work and jet lag 10 .

Circadin®, prolonged-release melatonin, is a prescription-only drug and the only melatonin drug approved by EMA, also showed extremely good effect on sleep-wake cycle readjustment as it mimics the body’s natural melatonin release profile. In a study on totally blind individuals trying to maintain a normal social lifestyle, the patients reported an improvement in sleep difficulties. 3 Moreover, it showed good results in treating jet lag and shift work sleep problems 11 12 .

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