The science of sleep and genes

Some people seem to manage quite happily on four hours of sleep a night while others turn into zombies. A new study by researchers at the University of Pennsylvania School of Medicine suggests that this may, in part at least, be down to our genes. They studied 129 healthy adults, 37 of whom, although unaffected, carried a gene called DQB1*0602 which is associatd with narcolepsy. The participants' sleep was restricted to four hours a night and they were given various tests of memory and attention. The people with the narcolepsy gene were sleepier and more fatigued while both fully rested and sleep deprived and they woke up more during the night; they also spent less time in deep sleep. However, there was no difference in their performance on the memory and attention tasks and in their ability to resist sleep during the daytime.