Did you know DNA influences your risk of narcolepsy?
Have trouble staying awake? It might be narcolepsy!
Remember that Friends episode where Chandler fell asleep at a meeting, and ended up with a job in Tulsa? How about the time the bus driver had to wake you up at the end of the line? Or that high school teacher who always fell asleep during detention? It happens to the best of us, often when meetings are called for in the afternoon, and when the caffeine is not in abundance. We are quick to blame big meals, not enough sleep, or lack of exercise for our afternoon slump, but what about our genes? Our genes can most definitely influence how much sleep we need. In extreme cases, genetic differences can even lead to sleep disorders. Narcolepsy is one such example, which is influenced by changes in the HLA-DQB1 gene.
Sleep is one aspect of our biology that still remains a bit of a mystery. Depending on how long we sleep, we go through four to six separate sleep cycles. Each cycle lasts about 100-110 minutes with two distinct phases called non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. We enter REM sleep about 70-90 minutes after falling asleep and during REM sleep the brain becomes active. During this stage, we dream and experience temporary muscle paralysis.
People with narcolepsy enter REM sleep just a few minutes after falling asleep. This helps to explain the symptoms associated with narcolepsy – sleep paralysis, vivid hallucinations and collapsing into a sleep-like state while remaining conscious (cataplexy). Have you ever woken up in the middle of a bad dream, unable to scream or move? If you have, that very brief moment of sleep paralysis and cataplexy was probably enough for you to realize how terrifying the symptoms of narcolepsy can be.
Cataplexy can be triggered by just an emotion. It can be extremely dangerous in some situations, like driving or crossing the street. Even with their involuntary daytime naps, people with narcolepsy are sleep-deprived, because their night sleep is interrupted by frequent awakenings. Adding insult to injury, a long list of health risks, including high blood pressure, obesity and decreased resistance to viral infections, are also associated with sleep-deprivation.
One way to diagnose narcolepsy is by looking at the levels of the neurotransmitter hypocretin (also called orexin). This is a chemical produced in the brain that controls alertness and prevents REM sleep. Individuals with cataplexy have lower levels of hypocretin, because the nerve cells (neurons) that produce hypocretin have died off. Over 90% of these patients also have genetic changes in the HLA-DQB1 gene, which is thought to play a role in regulating hypocretin levels. The HLA-DQB1 gene normally encodes a protein that is involved in signalling the immune system against foreign bodies (e.g. bacteria and viruses). However, a different version of HLA-DQB1 gene encodes a protein that may recognize the hypocretin-producing cells as being foreign, and signals for them to be killed. Genetic changes in HLA-DQB1 predispose individuals to narcolepsy, increasing the risk of developing narcolepsy by 7- to 25-fold.
There is no cure for narcolepsy, but the symptoms can be managed through medications that improve the level of alertness. A large proportion of us don’t get the recommended eight hours of sleep a night and are most likely sleep-deprived. However, to experience what a non-medicated narcoleptic feels like every day, you would have to stay awake for two to three days straight!
More than 250,000 Americans have narcolepsy, but only 25% of these cases are accurately diagnosed. It is often mistaken for depression, epilepsy or bipolar disorder, or simply dismissed as laziness. Our DNA Narcolepsy Test is a useful tool to help with an accurate narcolepsy diagnosis.