Getting too little sleep is linked to poor health, but short naps might partly offset that effect, a small study suggests.
Sleep deprivation can have a negative impact on brain function, metabolism, hormones and the immune system. The current study is the first to examine whether napping has any impact on stress or immune system function, said Brice Faraut, a sleep researcher at Université Paris Descartes-Sorbonne Paris Cité in France.
Faraut and colleagues studied 11 healthy young men who typically slept seven to nine hours each night, didn’t smoke and didn’t normally take naps.
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.
Based on urine and saliva samples, 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 levels, which dropped when the men were sleep-deprived but stayed normal when they were allowed to nap.
This relatively short nap duration can be a “powerful countermeasure to sleep debt,” Faraut said in an email, adding that the findings need to be tested in real-life situations.
Michael Grandner, a sleep researcher at the University of Pennsylvania who was not involved in the study, said the immune findings were somewhat contradictory to the existing literature.
“But these are complicated processes, and studies like these, that examine what happens during partial recovery, (help) us understand all of the ways that sleep is important for health and functioning,” Grandner told Reuters Health by email.
The findings were reported February 10 online in the Journal of Clinical Endocrinology and Metabolism.