Napping strengthens the body
Larissa Melville completed her traineeship in the editorial team of . After studying biology at Ludwig Maximilians University and the Technical University of Munich, she first got to know digital media online at Focus and then decided to learn medical journalism from scratch.
More about the experts All content is checked by medical journalists.MunichLack of sleep not only makes you unfocused, weak and irritable, it even makes some people sick. How much sleep someone needs, however, varies. The good news: power napping replenishes reserves.
If you haven't got enough sleep at night, you can help yourself with a short nap during the day - it is well known that it wakes you up again. French researchers have now found further facts that speak in favor of an afternoon nap: It regenerates the immune system and lowers the level of stress.
Messenger substances in urine and saliva
"Our data suggest that a 30-minute nap can reverse the negative effects of poor sleep," says Brice Faraut, PhD, of the Université Paris Descartes-Sorbonne Paris Cité. This applies in particular to the messenger substances in the body that have got into trouble due to lack of sleep.
In their study, they examined the effect of napping on the immune system and stress levels in eleven men between the ages of 25 and 32. To do this, the researchers exposed the participants to two different sleep settings - with a day of relaxation in between. Both times the subjects were only allowed to sleep for two hours at night, but once they were allowed to lie down for 30 minutes each in the next morning and afternoon. The researchers measured what happened in the body using certain biomarkers in saliva and urine - including interleukin-6, catecholamines, norepinephrine, norepinephrine and dopamine.
Stress hormones decrease
The result: After the short night, the concentration of the stress hormone norepinephrine increased 2.5 times. The nap caused the values to drop again. Norepinephrine plays a big role in the stress response: it increases heart rate, blood pressure and blood sugar. The immune system also benefited from napping. It normalized interleukin-6 levels. This messenger substance supports the immune system.
"Taking a short nap can potentially reduce the harmful effects of sleep deprivation as it helps both the immune and neuroendocrine systems to recover," says Faraut. The researchers hope that their investigation can help people who are prone to sleep deprivation.
Sleep needs vary
Because how much sleep someone needs is very different. A specially composed panel of experts has now published new recommendations for optimal sleep duration on behalf of the National Sleep Foundation. These vary greatly depending on age:
- Newborns (0-3 months): 14-17 hours
- Infants (4-11 months): 12-15 hours
- Infants (1 - 2 years): 11 to 14 hours
- Pre-school children (3 - 5 years): 10 to 13 hours
- School-age children (6-13 years): 9-11 hours
- Teenagers (14-17 years): hour to 8 to 10 hours
- Young adults (18-25 years): 7 to 9 hours
- Adults (26-64 years): 7 to 9 hours
- Older adults (65+ years): 7 to 8 hours
The specifications are based on the results of a meta-analysis of 320 studies. These investigated the health consequences of too much or too little sleep for healthy people.
Many questions are still open
The recommendations are a good guide. But sleep itself still poses a number of puzzles to scientists. "We still have a lot to learn about the function of sleep," says Dr. Lydia DonCarlos, neuroendocrinologist from Loyola University and a member of the expert panel. "We know that sleep is restful and important for memory. But even though we spend a third of our lives sleeping, we don't know the exact functions of sleep, ”she adds.
Sources:
Press release of the Loyola University Health System from 02/11/2015
National Sleep Foundation, sleepfoundation.org, (accessed on February 12, 2015)
Press release of the Endocrine Society from 02/10/2015
Brice Faraut et al .: Napping Reverses the Salivary Interleukin-6 and Urinary Norepinephrine Changes Induced by Sleep Restriction. The Journal of Clinical Endocrinology & Metabolism. doi: 10.1210 / jc.2014-2566
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