Some people naturally are night owls, while others appear to be early birds. There are good sleepers, and there are poor sleepers. These all might be traits that are inherited, or at least have some genetic disposition.
Some people have childhood-onset insomnia. Other are “born insomniacs”. Just as Gayle Greene, author of Insomniac, appears be. Based on her mother’s letters/journals, she didn’t sleep much as a baby. Greene talked to many sleep research and many other insomniacs for her book, and there are accounts of “born as an insomniac”.
So there must be some genes involved. And there is concordance of sleep pattern in twins. But it is not that simple, Greene writes…
“But sleep is a complex behavior governed by a multiplicity of genes, each contributing some small part, some to the timing and some to the sleep pressure, some that are known and many that remain undiscovered. A predisposition to insomnia might involve genes that influence, say, the sensitivity of the GABA receptors or the action of adenosine, or genes that set the speed of the metabolism or affect parts of the sleep-wake system we know nothing about, each making its own contributing, each interacting with and influenced by environmental factors. “
On the one extreme, there is “fatal familial insomnia”, which is “is an extremely rare autosomal dominant inherited prion disease of the brain” caused by a mutated protein. It affect about 100 people worldwide and “if only one parent has the gene, the offspring have a 50% risk of inheriting it and developing the disease.” [wikipedia] Unfortunately, after the onset of the disease (usually around middle age from 18 to 60), they have about 7 to 36 months to live as their sleep progressively gets worse and simple can not sleep at all. There is no cure. Autopsy show atrophy of the thalamus.
What are the genes involved in sleep?
Just some of the genes involved in sleep are the circadian genes called “clock”, “tim”, and “per”. They regulate our biological clock.
Another genetic component that affects sleep is how efficient an enzyme called adenosine deaminase breaks down adenosine, and how efficiently adenosine is produced. Adenosine is a neurotransmitter responsible for sleep pressure. As time goes on when you are awake, you accumulate more and more adenosine and the sleepier you get. When sleep comes, adenosine deaminase breaks down the adenosine.