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.

Comparing Sleep And Awake Schedules

The newer blue-enriched lights used in light boxes are no more effective at advancing circadian rhythms than the standard white lights that have been in use for decades according to a study by researchers in the Rush University Medical Center Biological Rhythms Research Lab. The study results will be published in the journal Sleep Medicine Vol. 10, issue 3 (April 2009).
These results are important for people who use therapeutic light boxes and scheduled exposure to light and darkness to rest their natural body clocks, such as shift workers and those who have certain sleep issues like delayed sleep phase disorder (DSPD), a condition in which an individual has a biological predisposition to go to bed and awaken on a much later schedule than most people.
Previous research has shown that the human circadian clock is most sensitive to short-wavelength (blue) light, but more research is needed regarding the dosage, timing and wavelength of light treatment.
Researchers at Rush were interested in finding out if bright blue lamps would provide a larger phase advance, or help patients awaken earlier, than the standard bright white lamps commonly used for phase shifting. The study found the blue lamps were no more effective than the standard bright therapy.
“This is good news for people using light treatment because it indicates that the standard white lights that are commercially available work as well as the newer blue-enriched lights. It means that patients are already likely getting a maximal therapeutic response, so there’s no need to rush out and buy a new light box,” said lead author Mark Smith, post-doctoral fellow in the Biological Rhythms Research Laboratory at Rush University Medical Center.
In the study, twenty-two healthy young adults received either a bright white or bright blue-enriched two-hour phase advancing light pulse upon awakening on each of four treatment days. On the first treatment day, the light pulse began eight hours after the dim light melatonin onset, on average about two hours before baseline wake time. On each subsequent day, light treatment began one hour earlier than the previous day, and the sleep schedule was also advanced.
Following the four treatment days, a final phase assessment was conducted. Phase advances of the blue-enriched and white groups were not significantly different.
The effectiveness of the blue-enriched lights at a different light level—less bright—for treatment of different clinical applications, was not tested in this study. According to study authors, blue-enriched lights may be useful for other clinical conditions.