Circadian Rhythm Sleep Disorder
Circadian rhythms, often referred to as our “internal body clock”, are 24 hour cycles that our bodies naturally work to. Circadian rhythm sleep disorders (CRSDs) are a group of sleeping disorders that result from abnormalities in circadian rhythm. These disorders make being able to sleep and wake at times normally needed for work and social requirements extremely difficult or impossible to do.
Causes of the Circadian Rhythm Sleep Disorder
The causes of CRSD may be due to an intrinsic problem in the “internal body clock” or due to the “internal body clock” not being synchronised with the external environment. Circadian rhythms are primarily set by light. Light signals are sent from the eyes to the suprachiasmatic nuclei (SCN), which is the area of the brain that regulates circadian rhythms. The SCN tells the pineal gland when to make and release a hormone called melatonin. Melatonin makes us feel sleepy and normally increases with darkness.
CRSDs can be caused by:
- Problems in sending or receiving light signals (e.g. blindness and SCN lesions)
- Trying to sleep during the day (e.g. night-shift workers)
- Issues in making or releasing melatonin (e.g. pineal gland defects).
Medical Treatment of Circadian Rhythm Sleep Disorder
There are no cures for CRSDs but a range of strategies can be used to help treat the condition.
- Bright light therapy – Circadian rhythms can be altered by using very high light intensity (> 10,000 lux; equivalent to direct sunlight). The timing and intensity of bright light therapy is tailored to the need of the patient, with patients needing to fall asleep earlier being given therapy earlier during the day, with therapies typically lasting 1-2 hours/day until the desired result is achieved.
- Melatonin – Melatonin or medications such as Tasimelteon (which increases melatonin production) may be prescribed to help with CRSDs. The effectiveness of these drugs depends on the type of CRSD and should only be used as directed by a medical professional.
- Pharmacotherapy – Stimulants such as caffeine or modafil can be used to increase alertness during the day but may negatively impact sleep. Hypnotics such as zolpidem can be used to promote sleep but typically have more severe side-effects than melatonin.
Alternative Approaches to the Treatment
- Behaviour therapy – This is typically the first step taken and includes not napping, maintaining regular awake-sleep routines, avoiding stimulants (e.g. nicotine and caffeine) and minimizing light exposure during the evening and night.
- Blue-light blocking sunglasses– Sleep can be aided by wearing specialised sunglasses that block blue light in the evening. Blue light potently suppresses melatonin levels and is released by energy saving-light bulbs and computer screens.
- Exercise – Exercise can improve the length and quality of sleep in a number of studies, particularly moderate aerobic exercise. The best time to exercise to improve sleep quality is in the afternoon or early evening but exercising in the morning can have positive effects on sleep. Benefits can be seen after a single workout but for some people it may take up to 8 weeks to see results.
The amino acid tryptophan (found at high concentrations in soybeans, sesame seeds, and chickpeas) can be converted to melatonin in the brain. This effect needs carbohydrates and insulin. Whole grains and oats are good carbohydrate sources, while honey can increase insulin levels in a healthily.
Other suggested foods:
Elk has the highest tryptophan content of meat and calcium in the form of dairy products (e.g. milk and cheese) can help the uptake of tryptophan. Additionally, fish such as tuna and salmon are high in vitamin B6 which is needed to make melatonin.
Vitamins and minerals help to treat Circadian Rhythm Sleep Disorder
Calcium and vitamins B6 and B12 are important for the synthesis of melatonin and serotonin which also helps maintain good sleep quality. Good sources of calcium include kale and blackstrap molasses, with raw garlic and pistachio seeds good sources of vitamin B6 and vitamin B12 found at high levels in fortified soy milk and tofu.