Napping Reverses Increased Pain Sensitivity Due to Sleep Restriction

Abstract

Study ObjectiveTo investigate pain sensitivity after sleep restriction and the restorative effect of napping.DesignA strictly controlled randomized crossover study with continuous polysomnography monitoring was performed.SettingLaboratory-based study.Participants11 healthy male volunteers.InterventionsVolunteers attended two three-day sessions: “sleep restriction” alone and “sleep restriction and nap”. Each session involved a baseline night of normal sleep, a night of sleep deprivation and a night of free recovery sleep. Participants were allowed to sleep only from 02:00 to 04:00 during the sleep deprivation night. During the “sleep restriction and nap” session, volunteers took two 30-minute naps, one in the morning and one in the afternoon.Measurements and ResultsQuantitative sensory testing was performed with heat, cold and pressure, at 10:00 and 16:00, on three areas: the supraspinatus, lower back and thigh. After sleep restriction, quantitative sensory testing revealed differential changes in pain stimuli thresholds, but not in thermal threshold detection: lower back heat pain threshold decreased, pressure pain threshold increased in the supraspinatus area and no change was observed for the thigh. Napping restored responses to heat pain stimuli in the lower back and to pressure stimuli in the supraspinatus area.ConclusionsSleep restriction induces different types of hypersensitivity to pain stimuli in different body areas, consistent with multilevel mechanisms, these changes being reversed by napping. The napping restorative effect on pain thresholds result principally from effects on pain mechanisms, since it was independent of vigilance status.

Night-shift work is associated with increased pain perception

“…Our finding of unchanged pressure-pain sensitivity following NSW contrasts with earlier studies of experimental sleep restriction (18,19,42). Relative to the previous study from our lab, the present study population were somewhat older.…”

“…The present subjective sleepiness of night-shiftinduced sleep restriction is comparable to that reported by experimental sleep restriction studies (17)(18)(19), indicating that experimental sleep restriction studies may be a valuable model to study the effect of nightshift-induced effects on sleep.…”

“…Prospective studies indicate that sleep problems are associated with an increased risk for longlasting musculoskeletal pain (9)(10)(11)(12)(13)(14)(15) and experimental studies suggest that even a relatively modest restriction or disturbance of sleep increases pain sensitivity. This is manifested as larger responses to experimentally induced pain (16)(17)(18)(19)(20)(21), as increased spontaneous pain (22)(23)(24), or as altered pain modulation (23,(25)(26)(27)(28)(29). A recent meta-analysis confirm that sleep restriction increases sensitivity for several types of pain (30).…”

The effect of sleep deprivation on pain perception in healthy subjects: a meta-analysis

“…In a sample of 24 women, Wright et al [80] found that lower sleep efficiency is a significant predictor of greater pain severity after breast-surgery. The hyperalgesic effect of sleep deprivation seems reversible by napping [81] as well as by effective treatment of sleep disorders [17]. Roehrs et al [82] showed that extended sleep reduces pain sensitivity and poor sleep quality is a risk factor for the development of chronic widespread pain [83].…”

Napping: A public health issue. From epidemiological to laboratory studies

“…[189][190] In healthy subjects, most of the sleep restriction studies devoted to pain have shown that it was associated with increased pain intensity or a decreased pain threshold. [191][192][193] Pain tolerance and perception are certainly influenced by alertness levels. Sleep loss enhances hyperalgesia, probably by acting on pain-inhibiting/facilitating physiological pathways, but less is known about the effects of napping on these pathways.…”