Scientific Basis for Benefits of Napping

Evidence exists to document the deleterious effects of too little sleep – ranging from disturbances to cognitive processes to a compromised immune system.  Brice Faraut, from Universite Paris Descartes-Sorbonne (France), and colleagues enrolled 11 healthy young men who typically slept seven to nine hours each night, didn’t smoke and didn't normally take naps, to undergo a controlled sleep study.  Two separate times, each man participated in a three-day session of sleep tests in a laboratory where food intake and lighting were strictly controlled and no alcohol, caffeine or medications were allowed.  During one session, they slept normally for one night but then were only allowed to sleep for two hours the next night. The men could sleep as much as they liked on the third night.  The other session was the same - except the men were allowed to take two 30-minute naps the day after their sleep was restricted. The researchers collected urine and saliva samples each day to measure levels of norepinephrine, elevated levels of which signal stress.    The team observed that the men’s norepinephrine levels were more than doubled in the afternoon after the night of sleep restriction, compared to the day after they had slept normally. But there was no change in norepinephrine when participants were allowed to nap.  Lack of sleep also affected interleukin-6, an immune-regulating molecule; levels of it dropped when the men were sleep-deprived but stayed normal when they were allowed to nap.  Writing that: “Our data suggest that napping has stress-releasing and immune effects.,” The study authors submit that: “Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.”