Napping Reverses the Salivary Interleukin-6 and Urinary Norepinephrine Changes Induced by Sleep Restriction

• Published in: The journal of clinical endocrinology and metabolism Vol. 100; no. 3; pp. E416 - E426
• Main Authors: Faraut, Brice, Nakib, Samir, Drogou, Catherine, Elbaz, Maxime, Sauvet, Fabien, De Bandt, Jean-Pascal, Léger, Damien
• Format: Journal Article
• Language: English
• Published: United States Endocrine Society 01-03-2015; Copyright by The Endocrine Society
• Subjects: Adult; Cross-Over Studies; Humans; Interleukin-6 - metabolism; Male; Monitoring, Ambulatory - methods; Norepinephrine - urine; Polysomnography; Saliva - metabolism; Sleep - physiology; Sleep Deprivation - metabolism; Sleep Deprivation - urine; Wakefulness - physiology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2014-2566

Context:
Neuroendocrine and immune stresses imposed by chronic sleep restriction are known to be involved in the harmful cardiovascular effects associated with poor sleep.
Objectives:
Despite a well-known beneficial effect of napping on alertness, its effects on neuroendocrine stress and immune responses after sleep restriction are largely unknown.
Design:
This study was a strictly controlled (sleep-wake status, light environment, caloric intake), crossover, randomized design in continuously polysomnography-monitored subjects.
Setting:
The study was conducted in a laboratory-based study.
Participants:
The subjects were 11 healthy young men.
Intervention:
We investigated the effects on neuroendocrine and immune biomarkers of a night of sleep restricted to 2 h followed by a day without naps or with 30 minute morning and afternoon naps, both conditions followed by an ad libitum recovery night starting at 20:00.
Main Outcome Measures:
Salivary interleukin-6 and urinary catecholamines were assessed throughout the daytime study periods.
Results:
The increase in norepinephrine values seen at the end of the afternoon after the sleep-restricted night was not present when the subjects had the opportunity to take naps. Interleukin-6 changes observed after sleep deprivation were also normalized after napping. During the recovery day in the no-nap condition, there were increased levels of afternoon epinephrine and dopamine, which was not the case in the nap condition. A recovery night after napping was associated with a reduced amount of slow-wave sleep compared to after the no-nap condition.
Conclusions:
Our data suggest that napping has stress-releasing and immune effects. Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.