Fig 1.
The experimental design included two three-day sessions, during which continuous ambulatory polysomnography (PSG) recordings were taken for each volunteer. The volunteers were randomly allocated to two groups, one of which started with the “sleep restriction” session, the other group beginning with the “sleep restriction + nap” session. In the “sleep restriction” session, the volunteers were allowed to sleep for only two hours during one night (in bed from 02:00 to 04:00), the previous night of 8 hours of sleep being used as the baseline (in bed from 00:00 to 08:00). The night after sleep deprivation, the volunteers were allowed to sleep from 20:00 until spontaneous awakening, for recovery. In the “sleep restriction + nap” session, the volunteers repeated the protocol described for the sleep restriction only session, but were allowed to take 30-minute naps at 09:30 and 15:30 on the day following the night of sleep restriction. Subjective sleepiness was assessed and QST was carried out each day, at 10:00 and 16:00.
Table 1.
Lower back quantitative sensory testing profile after sleep restriction without or with napping.
Table 2.
Supraspinatus quantitative sensory testing profile after sleep restriction without or with napping.
Table 3.
Supraliminal thermal stimulation in supraspinatus area after sleep restriction without or with napping.
Table 4.
Thigh quantitative sensory testing profile after sleep restriction without or with napping.
Table 5.
Stanford sleepiness scale after sleep restriction without or with napping.
Fig 2.
Changes in heat pain, pressure pain and sleepiness without or with napping after sleep restriction.
We assessed the effects of napping, by comparing the different sleep restriction conditions (“sleep restriction” session and “sleep restriction + nap” session), using normalized delta scores for each sleep restriction condition relative to the corresponding baseline. Changes are shown for heat pain (A), pressure pain (B) and sleepiness (C). Sleep restriction increased sleepiness and decreased pain tolerance, whereas napping reversed the increase in pain sensitivity but did not decrease sleepiness (due to sleep inertia). Mean ± SEM; * indicates significant differences between conditions.