Mitigating Sleep Inertia and Maintaining Neurobehavioral Performance in Shift Workers via Multisensory (Music and Light) Intervention: A Preliminary Field Study

Irregular shift schedules in railway operations increase safety risks through fatigue and sleep inertia. We evaluated a wearable multisensory device that delivers sleep-promoting music in darkness before sleep and uplifting music with blue light upon awakening. In a preliminary field crossover study, 17 railway staff completed the Psychomotor Vigilance Task (PVT), Karolinska Sleepiness Scale (KSS), and Positive and Negative Affect Schedule (PANAS) before and after on-duty sleep, with and without the device. In a separate electroencephalography (EEG) study, 10 healthy adults received sleep-onset and wake-up stimulation while EEG was recorded at Fz, Cz, and Pz. Compared to the control condition, the intervention maintained PVT response speed, reduced lapses at the end of the shift, and was associated with longer sleep duration. The PVT results, but not positive affect, remained significant after adjustment for pre-sleep values. Sleepiness was not significantly reduced overall and was lower only in an exploratory station subgroup. In the EEG study, the slow-to-fast power ratio increased during sleep-onset stimulation, and theta power was transiently lower early in wake-up stimulation than at the end of sleep-onset stimulation. These preliminary findings suggest that dual-phase multisensory stimulation may help sustain alertness in shift workers, although larger sham-controlled trials are needed.