Insomnia is a sleep disorder characterized by difficulty falling asleep, staying asleep, or both.

The genetics of insomnia are complex and not fully understood, but several genetic variations have been associated with an increased risk of developing the condition. These include variations in genes involved in the regulation of the sleep-wake cycle, such as CLOCK, PER3, and CRY1, as well as genes involved in neurotransmitter function, such as 5-HTTLPR and TPH2. Some studies have also suggested a link between insomnia and certain genetic variations involved in the body's response to stress. However, it is important to note that genetics are just one factor that contribute to the development of insomnia, and many other factors such as environmental, psychological, and lifestyle also play a role.