Conventional wisdom used to be that you can never catch up on a lost night of sleep — but a new study adds weight to the emerging theory that the negative health effects of a sleepless night can actually be reversed by a good nap.
In a small study of 11 healthy men published in the Journal of Clinical Endocrinology & Metabolism (JCEM), researchers found that even if the men got only two hours of sleep the night before, they could combat the hormonal havoc caused by poor sleep if they took a couple of brief naps.
To reach these results, the researchers had the men undergo two sleep sessions in a lab. In the first, the men only got two hours of sleep and then had their urine and saliva measured and analyzed for hormonal changes. In the second session, the men once again only got two hours of sleep, but this time they also took two 30-minute naps the following day. The men provided saliva and urine samples once again.
The study found that when men only slept for two hours, they had a 2.5 increase in norepinephrine, a hormone and neurotransmitter which responds to stress. That increase can up the body's heart rate and blood pressure. The men also had low levels of the protein interleukin-6 which is critical for having a proper immune response. However, when the men were sleep-deprived but napped the following day, the researchers found there were no changes in either their protein or hormone levels.
According to the researchers, the findings suggest that taking a nap can restore out-of-whack hormone levels, and improve immune system health. But to avoid the sluggishness and medical problems that can come from from not getting enough shut eye, try to get the recommended amount of sleep every night. For adults, that's 7 to 9 hours.