0166 Exposure to Blue-Enriched Light Following a 1-Hour Nap Extends Duration of Benefits to Sleepiness and Performance

Abstract Introduction When an unavoidable work task occurs during the night, workers must be sufficiently alert to perform safely. Both blue-enriched lighting and napping improve alertness and performance at night, but it is unclear how much or how long each intervention contributes to such improvements. We conducted a study to evaluate these interventions separately and together. Methods Participants completed two 26-hour laboratory visits, each following a week of 8.5 h time-in-bed (verified by actigraphy), where they completed an hourly 5-minute psychomotor vigilance task (PVT) and sleepiness visual analog scale. Participants were randomized by visit to undergo a control condition involving a 1-hour awake rest period under 150 lux lighting (rest+150) and one of three experimental conditions involving either 1) a 1-hour nap opportunity followed by 150 lux (nap+150), 2) a 1-hour nap opportunity followed by 250 melanopic EDI (mEDI; nap+250), or 3) a 1-hour rest period followed by 250 mEDI (rest+250). Each intervention began 20 hours after habitual waketime and the lights remained on post-nap/rest until discharge 7 hours later. We compared outcomes on the seven tests following the nap/rest between conditions using linear mixed-effects models with participant as a random effect, and age and sex as covariates, and performed post-hoc comparisons of each post-nap/rest test bout relative to the test immediately before the nap/rest. Results Thirty-two participants completed the study (16 female; MAge ± SD = 24 ± 5 years). Compared to control, participants rated their sleepiness as lower following a nap (nap+250 β=-14.3,p< 0.001; nap+150 β=-15.4,p< 0.001) and had faster PVT speeds (nap+250 β=0.21,p< 0.001; nap+150 β=0.23,p< 0.001), but there was no improvement in the rest+250 condition. Post-hoc analyses comparing each post-nap/rest test to the pre-intervention test revealed significantly lower sleepiness ratings 2-5 hours after a nap+250 (compared to control) and faster PVT speed at each hour (1-7) after nap/rest end. PVT speed was also better than control 1-4 hours after wake in the nap+150 condition. The rest+250 condition was not different. Conclusion Our preliminary results suggest that a short nap at night improves subsequent reaction time, while blue-enriched light sustains these effects. Support (if any) This study was funded by the NASA Human Research Program.