A fragmented sleep increase pain sensitivity in healthy subjects

Background and aims: Poor quality of sleep and chronic pain are common comorbidities, and their coexistence is associated with increased pain and a higher burden of disease. Experimental sleep provocations in healthy subjects have been suggested to affect central pain mechanisms. Previous experimental sleep provocations have generally included components of sleep deprivation, and there is limited evidence of how sleep fragmentation with no restriction on total sleep time impacts pain sensitivity. Thus, this study aimed to investigate the effect of three nights with sleep fragmentation on pain mechanisms.

Methods: Three nightly awakenings for three consecutive nights were planned for 30 healthy subjects. Sleep-associated parameters were assessed with a sleep diary. Pressure pain thresholds were investigated on the infraspinatus and gastrocnemius muscles, bilaterally. Cuff-pressure pain detection and tolerance thresholds, temporal summation of pain, and conditioned pain modulation were determined using computerized cuff-pressure algometry. Suprathreshold pain sensitivity was investigated on the dominant infraspinatus muscle using a handheld pressure algometer to provide a tonic pressure of 120% of the pressure pain threshold for 5 and 60 seconds.

Results: Sleep quality and level of rest were significantly lowered during sleep fragmentation compared to baseline (p<0.005). Following sleep fragmentation pressure pain thresholds were decreased at all measured points (p<0.005), temporal summation of pain was facilitated (p=0.022), and suprathreshold pain areas (p=0.005) and intensities (p<0.05) were increased compared to baseline.

Conclusions: Three nights with fragmented sleep induced increased pressure pain sensitivity and increased measures of pain facilitation.