A study published in the March issue of The Journal of Clinical Endocrinology & Metabolism (JCEM) indicates that short-term napping is able to restore, to a great extent, the neurohormonal and immune changes induced by sleep deprivation.
Insufficient sleep is well-known to be associated with poor attention and performance deficits.
However, an increasing body of evidence suggests that insufficient sleep in humans also influences metabolic, hormonal and immune homeostasis. This, in turn, may affect cardiovascular health, and increase the risk of coronary heart disease, impaired glucose tolerance or the development of diabetes (Janet M Mullington et al., 2009). In mice, lack of sufficient sleep resulted in accelerated tumor growth (Fahed Hakim et al., 2014).
In the JCEM study, Brice Faraut and colleagues from the Paris Descartes University – Sorbonne Paris Cité, Paris, France report that a night of sleep restricted to 2h resulted in a 2.5-fold increase in 24h-urinary norepinephrine (noradrenaline) levels, and a reduction of salivary interleukin (IL)-6 levels.
The day after the sleep deprivation, however, two 30 minute morning and afternoon naps were able to reverse the neurohormonal and immune changes induced by a night of poor sleep. These observations substantiate a 2007 study by Vgontzas et al., showing that a short mid-afternoon nap reversed the effects of one night of sleep loss on cortisol and IL-6 changes.
These studies indicate that napping may counterbalance sleep deprivation and its stress-induced effects by restoring the immune and neurohormonal ‘milieu intérieur’ or homeostasis.