By Dr.Manvir Bhatia/Saunri, Sleep, Genetics
Whether you get a good night’s sleep depends on numerous characteristics. Sleep is an extremely complex behaviour. It is divided into Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM) sleep. Dreaming occurs during REM sleep and is important to help us process our emotions. The circadian rhythm and homeostasis are the biological mechanisms that work together to regulate sleep. While factors such as increased screen time, intake of caffeine before bed, lack of physical exercise etc, may leave you tossing and turning and bed, or with insomnia, the question you can ask is whether your poor sleep is all because of your poor sleep hygiene or does poor sleep have a genetic component and is it hereditary?
Kids require around 9.5 hours of sleep daily whereas it varies from 7-9 hours in an adult. For older people above the age of 60, the amount of night sleep decreases and is interrupted frequently. Getting regular, quality sleep is an important part of our daily routine for normal functioning and is necessary for vital functions such as memory formation.
Genetic Component of Sleep
Although a definite set of genes that control sleep are not yet known, there are a few genes that play an important role in maintaining the circadian rhythm. These include the clock genes e.g. Per, Tim, etc. There is also evidence that heredity plays an important role in the quality and quantity of our sleep by the fact that sleep studies have shown that identical twins (that share the same genetic material) have similar hypnograms or sleep graphs.
Sleep Disorders and Genetics
Very often it has been observed that there is a family history of sleep onset and sleep maintenance disorders.
Insomnia: It is a sleep disorder that makes it difficult for the person to fall asleep difficult to stay asleep and difficult to sleep again after waking up at night. About 35% of people that suffer from insomnia have a positive family history. Most often, the mother of the person suffering from Insomnia has also been affected with Insomnia.
Fatal Familial Insomnia: It is a rare brain disorder, which is caused by a mutation in the PRNP gene and leads to the degeneration of the brain. It is mostly transmitted genetically and it is very rare for a person without a family history of Fatal Familial Insomnia to suffer from it.
Restless legs syndrome (RLS): It is a sleep disorder in which a person experiences an uncomfortable feeling and has the uncontrollable urge to move the legs when he is resting or is inactive. It generally occurs in the evening or at night. Around 40-60% of patients suffering from RLS have a family history of it. Earlier onset of the condition is observed in persons with a positive family history.
Genetic linkage studies indicate that RLS1 on chromosome 12q, RLS2 on 14q, RLS3 on chromosome 9p, RLS4 on chromosome 2q; and RLS5 on chromosome 20p are the known chromosome loci that play a role in this disorder. Identical twins often share similar symptoms of RLS.
Periodic Limb Movement Syndrome (PLMS): PLMS is a condition of sleep in which the limbs move involuntarily every 10 to 20 seconds while sleeping. It is strongly associated with four genes: MEIS1, BTBD9, MAP2K5, and SKOR1. The genetic variants of these alleles pose a 50% risk for RLS. Variation in BTBD9 alleles is associated only with PLMS. It is indirectly associated with RLS as it decreases ferritin levels and poses a risk for onset of RLS.
Hence, we can conclude that indeed poor sleep is hereditary. There are some genes that when inherited put the person at a greater risk of developing certain sleep disorders. Thus, it is necessary to trace a patient’s family history in order to manage and treat their sleep disorder effectively.
To seek help or know more about sleep and its genetic factors, you can visit the Neurology and Sleep Centre, the 1st sleep centre in the country accredited by Indian Board of Sleep Medicine at L-23, Hauz Khas Enclave, New Delhi, Delhi-110016 (INDIA)
Or give a call on +91-11-46070321, +91-9643500270
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