Insomnia is not an inherited condition, but some predispositions that can lead to insomnia can be genetic. Recent investigation into the human genome has found epigenetic mechanisms involved in both sleep regulation and insomnia.
A large population study found that insomnias tend to be physically smaller than normal sleepers: they have smaller skeletons and less lean body mass. Incidence of obesity is also higher. Insomnias are more often underweight and overweight. They also have a different blood analysis profile: levels of albumin are lower and insulin and triglycerides are higher. The ?-glutamyl transferase enzyme, frequently used as a diagnostic marker, is also higher in insomniacs, and this incidence, along with high insulin levels, can suggest diabetes. The study found insomniacs have diabetes in higher numbers than normal sleepers.
Insomnicas also tend to have high calcium levels in the blood – which has been shown to be associated with cognitive decline in the long run.
It’s accepted that genetics affect sleep patterns and at least somewhat determine which chronotype (e/g/ a morning lark, a night owl) a person is. What’s less clear is how genetics affects an individual’s response to sleep deprivation. As with alcohol, where some people can handle their alcohol without as many visible outward signs, some people seem better able to function when sleep deprived.
The PER3 gene is known to influence the circadian system, and one variant is associated with a lower homestatic sleep drive. While scientists do not say there is a direct connection, the findings imply people with this variant PER3(4/4) are vulnerable for insomnia. Scientists found a gene mutation named hDEC2-P385R which is a a transcriptional repressor and has been found to cause individuals to be short sleepers.
The federal government’s latest (2011) sleep disorders research plan articulates among its goals identification of genetic factors that influence the risk of sleep disorders. It is not easy to figure out the genetics and heritability of insomnia and other problems and scientists appear to be a long way from getting there although some clues have been discovered.