Ever wonder why some people breeze along on 4 hours of sleep when others can barely function? It may be in our genes, according to new research and an accompanying editorial published in the October 26, 2010, print issue of Neurology, the medical journal of the American Academy of Neurology.
The study looked at people who have a gene variant that is closely associated with narcolepsy. However, having the gene variant, called DQB1*0602, does not mean that a person will develop narcolepsy; depending on the population, 12% to 38% of those with the variant do not have the sleep disorder and are considered healthy sleepers. Also, people without the gene variant can develop narcolepsy, though this is less common.
Results of the study found that the people with the DQB1*0602 gene variant were sleepier and more fatigued while both fully rested and sleep deprived. Their sleep was also more fragmented. For example, those with the gene variant woke up on average almost four times during the fifth night of sleep deprivation, compared to those without the gene variant, who woke up on average twice. Those with the gene variant also had a lower sleep drive, or desire to sleep, during the fully rested nights.
Those with the gene variant also spent less time in deep sleep than those without the variant, during both the fully rested and sleep deprivation nights. During the second fully rested night, those with the variant had an average of 34 minutes in stage three sleep, compared to 43 minutes for those without the variant. During the fifth night of sleep deprivation, those with the variant spent an average of 29 minutes in stage three sleep, compared to 35 minutes for those without the variant.
The two groups performed the same on the tests of memory and attention. There was also no difference in their ability to resist sleep during the daytime.