Searching For Shut Eye: Study Identifies Possible Sleep Gene

While scientists and physicians know what happens if you don’t get six to eight hours of shut-eye a night, investigators have long been puzzled about what controls the actual need for sleep. Researchers at the University of Pennsylvania School of Medicine might have an answer, at least in fruit flies. In a recent study of fruit flies, they identified a gene that controls sleep.
“We spend -- or should spend -- a third of our lives sleeping,” says Amita Sehgal, PhD, Professor of Neuroscience and an Investigator with the Howard Hughes Medical Institute (HHMI). “The idea that so much time is spent in sleep is intriguing. Also, sleep deprivation has serious health consequences and impairs cognitive function.”
This study was published in the latest Science.
Fruit flies typically sleep 12 hours a day. Sehgal and her team studied 3,500 fruit flies and found mutants that survived on little to no sleep – one to two hours a day or none at all. The sleepless flies had a mutation of a gene that Sehgal and her team have named Sleepless. They believe the Sleepless gene encodes a protein that affects whether potassium ion channels in the brain stay open or closed. When the channels are open, the brain is connected and working – the fly is awake. When closed, the channel shuts down and the fly sleeps. The insomniac fruit flies had less of the Sleepless-produced protein.
The lack of sleep didn’t come without consequences. The Sleepless fruit flies lived about half as long as fruit flies that did not carry the mutation. They also experience impaired coordination and restlessness in their few hours of sleep.
Sleep is regulated by two processes: circadian and homeostatic. Circadian regulation affects the timing of sleep, and the homeostatic mechanism affects the need for sleep. The Sleepless gene affects the homeostatic mechanism.
Sleep isn’t just for humans – it’s been observed in everything from flies to dogs to people, indicating that it’s essential to life. Insufficient and poor-quality sleep is an increasing problem in industrialized nations. In the U.S. alone, about 70 million people suffer from chronic sleep problems, which reduce workplace productivity, affect quality of life and can even be lethal.
“In the long term, we hope that human equivalents of our gene will be isolated and will not only further our understanding of human sleep, but perhaps also serve as drug targets to promote sleep or treat insomnia,” says Sehgal.

The societal, economic burden of insomnia is high

The largest proportions of all insomnia-related expenses are attributed to lost job productivity, absences from work and alcohol used as a sleep aid.
A study in the Jan. 1 issue of the journal Sleep indicates that the indirect costs of untreated insomnia are significantly greater than the direct costs associated with its treatment. The study estimates that the total annual cost of insomnia in the province of Quebec is 6.5 billion Canadian dollars, representing about one percent of the province's $228.5 billion in gross domestic product for 2002.
Annual indirect costs of insomnia related to lost hours of productivity are estimated to be $5 billion, representing the largest proportion (76 percent) of all insomnia costs. The annual estimate of insomnia-related lost productivity is 27.6 days per year for individuals with insomnia syndrome, and 6.2 days per year for people with insomnia symptoms. The second-highest cost of insomnia is attributed to job absenteeism, with $970.6 million – 14.7 percent of the total economic burden of insomnia - estimated to be lost annually due to insomnia-related absences. Individuals with insomnia syndrome are absent from work an estimated 4.36 days per year because of insomnia.
Lead author of the study, Meagan Daley, PhD, professor of psychology and business, in Quebec City, Canada stated that costs associated with the use of alcohol as a sleep aid exceed those associated with consultations and the use of medications and over-the-counter products.
The total estimated annual cost of alcohol used for promoting sleep is $339.8 million, which is the highest direct cost, representing 60 percent of all direct costs and five percent of all insomnia-related costs. The annual cost of insomnia-related consultations with a health-care professional is estimated to be $85.3 million (32.6 percent of all direct costs and 2.9 percent of overall costs), and an estimated $16.5 million is spent annually on prescription medications for insomnia (only 2.8 percent of direct costs and less than one percent of overall costs). According to the authors the centralization of the health-care system in Quebec keeps salaries and capital costs relatively low, and most medications prescribed for sleep in Canada are inexpensive generic drugs.
Daley said, "This study demonstrated that it is not the costs associated with seeking out treatment (for insomnia), such as consulting health-care professionals or purchasing medications or over-the-counter products that constitute anywhere near the largest proportion of expenditures. Rather, indirect costs constitute the greatest proportion of all insomnia costs, with about ¾ of overall costs being due to lost work productivity."
This study was a part of a larger epidemiological study documenting the natural history of insomnia. A total of 948 randomly selected adults were chosen from the province of Quebec, Canada, to participate. The mean age of participants was 43.7 years. Sixty percent of participants were female. Volunteers completed questionnaires on sleep, health, use of health-care services and products, accidents, work absences and reduced productivity in the previous three months. Data were also obtained from the government-administered health-insurance board in Quebec regarding consultations and hospitalizations.