Effects of Selected Body Warming Interventions on Objective Sleep Characteristics in Women with Insomnia

Abstract

Previous research suggests that insomnia may be effectively treated with selected strategies aimed at the manipulation of core and skin temperatures prior to bedtime. PURPOSE: This study examined the effects of three different body warming interventions prior to sleep on objective sleep characteristics in women with established sleep disruption. METHODS: Eight women (age: 55.3±5.9 yrs) who suffered from a sleep maintenance disorder participated. Following sleep adaptation and baseline sleep characteristics (BL) evaluation nights, each subject completed three randomly assigned experimental 30-min body warming sessions within 30 min of bedtime ("lights-out") in a sleep research laboratory (trials spaced one week apart). Body warming interventions consisted of moderate intensity (75% of HRmax) cycle ergometry exercise (EX), and 40°C seated whole body (WB) and foot baths (FB). All-night polysomnography (Somnostar Alpha, Sensormedics) was used to assess sleep. Changes in core and skin (chest, foot) temperatures were assessed using rectal thermometry (YSI 4600, YSI) and dermal patches (Vitalsense, Mini-Mitter), respectively. RESULTS: Pre-bedtime experimental body warming sessions were successful to produce significant intervention-specific changes in core and skin temperature recordings (p<0.05). However, repeated measures ANOVA indicated no significant differences among trials for measures of sleep architecture, including minutes of NonREM (BL: 342±31; EX: 325±51; WB: 328± 41; FB: 316±63) and REM (BL: 67±32; EX: 56±30; WB: 51±23; FB: 57±27) (p>0.05). Similarly, markers of sleep continuity, including sleep efficiency (%) (BL: 86±8; EX: 85±11; WB: 87±8; FB: 86±14) and wakes after sleep onset (min) (BL: 51.6±32.2; EX: 39.1±23.4; WB: 36.6±22.5; FB: 41.4±31.6) were not different among trials (p>0.05). CONCLUSIONS: These preliminary findings failed to reveal a statistically significant sleep promoting effect of moderate intensity exercise and other passive body warming strategies prior to bedtime. However, when compared to baseline sleep, the observed directional changes in several sleep variables across the three treatments were consistent with improved sleep and indicate a need for additional research on the effects of body warming treatments on sleep. Supported by Center for Health Research Collaborating Faculty Scholar Award and NIH/NINR R01 NR008024