0184 Effects of Olfactory Stimuli on Vigilance and Sleepiness During Sleep Inertia: Preliminary Results

Abstract Introduction Sleep inertia is a transient period of impaired function upon waking and poses risks for workers who must act quickly after abrupt arousal. We examined whether exposure to an arousing odorant upon waking is associated with greater vigilance and less sleepiness compared to no odorant. Methods Thirteen adults (10F, mean age 25 ± 3.7 range 21-35 years) completed 2 nights of PSG-monitored sleep with four arousals, each after 5 minutes of continuous slow-wave or REM sleep. Participants were exposed to no odor or a proprietary scent blend (PSB) designed to stimulate the trigeminal system via room diffusion in a counterbalanced within-subjects design. The odorant was delivered throughout each 20-minute arousal from 30 seconds beforehand. Vigilance was measured with two 5-minute Psychomotor Vigilance Tests (PVT; variables: mean reaction time (RT) and lapse count) occurring 1 and 11 minutes into the arousals. Participants completed a Visual Analog Sleepiness Scale (VASS) at minute 17. Separate linear mixed models with random intercept for participants predicted PVT and VASS variables from odor condition, accounting for night and arousal number. PVT models included a variable for PVT number within arousals interacted with odor condition to test whether PSB accelerated task performance relative to no odor. Results A trend was seen for faster RTs in the PSB condition vs. null (PSB: M=679.5 ms ± 609.5; Null: M=858.9 ms ±1047.0), b = −173.31, SE = 90.44, t(172.65) = −1.93, p = .057. Night 2 (b = 446.86, p < .001) and later arousals (b = 93.19, p = .018) had significantly slower RTs. For lapses, Night 2 (b = 3.56, p < .001), later arousals (b = 1.19, p = .001), and timing (first vs. second) (b = -1.89, p = .02) were significant predictors. For VASS, Night 2 was associated with lower subjective sleepiness (VASS: M=84.2 ± 9.5); (Null M=82.6 ± 14.7); (b = -4.28, p = .025). No interactions were significant. Conclusion PSB exposure during nocturnal arousals showed a trend toward improved vigilance (faster RT) but not reduced sleepiness. These findings contribute to limited research on whether olfactory stimulation can mitigate sleep inertia. Support (if any) RI Commerce Corporation; P20GM139743