A Pilot Study of Light Exposure as a Countermeasure for Menstrual Phase-Dependent Neurobehavioral Performance Impairment in Women
Document Type
Article
Publication Title
Sleep Health
Publication Date
8-17-2023
Abstract/ Summary
Objective
To examine effects of menstrual phase and nighttime light exposure on subjective sleepiness and auditory Psychomotor Vigilance Task performance.
Methods
Twenty-nine premenopausal women (12 = Follicular; 17 = Luteal) completed a 6.5-hour nighttime monochromatic light exposure with varying wavelengths (420-620 nm) and irradiances (1.03-14.12 µW/cm2). Subjective sleepiness, reaction time, and attentional lapses were compared between menstrual phases in women with minimal (<33%) or substantial (≥33%) light-induced melatonin suppression.
Results
When melatonin was not suppressed, women in the follicular phase had significantly worse reaction time (mean difference = 145.1 ms, 95% CI 51.8-238.3, p < .001, Cohen’s D = 1.9) and lapses (mean difference = 12.9 lapses, 95% CI 4.37-21.41, p < .001, Cohen’s D = 1.7) compared to women in the luteal phase. When melatonin was suppressed, women in the follicular phase had significantly better reaction time (mean difference = 152.1 ms, 95% CI 43.88-260.3, p < .001, Cohen’s D = 1.7) and lapses (mean difference = 12.3 lapses, 95% CI 1.14-25.6, p < .01, Cohen’s D = 1.6) compared to when melatonin was not suppressed, such that their performance was not different (p > .9) from women in the luteal phase. Subjective sleepiness did not differ by menstrual phase (mean difference = 0.6, p > .08) or melatonin suppression (mean difference = 0.2, p > .4).
Conclusions
Nighttime light exposure sufficient to suppress melatonin can also mitigate neurobehavioral performance deficits associated with the follicular phase. Despite the relatively small sample size, these data suggest that nighttime light may be a valuable strategy to help reduce errors and accidents in female shift workers.