This randomized, parallel-group study will examine how artificial light exposure during nighttime awakenings affects sleep and brain health in midlife women experiencing vasomotor symptoms, such as hot flashes and night sweats. Participants will be randomly assigned to exposure to either typical indoor-intensity light (approximately 100 lux) or dim light (less than 3 lux) during the night. The study will assess the effects of nighttime light exposure on sleep fragmentation, daytime alertness and sleepiness, stress responses, cognitive and emotional functioning, and daily functioning. It will also explore whether sleep fragmentation helps explain the effects of nighttime light exposure on stress and neuropsychological health. The findings may inform strategies to reduce nighttime light exposure and improve sleep and brain health in women during and after the menopause transition.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
66
Participants will be exposed to a controlled artificial-light-at-night condition during the scheduled overnight sleep episode. Light will be delivered using a standardized light source at a predetermined intensity and timing to examine its effects on sleep, brain health, and related physiological outcomes in midlife women with vasomotor symptoms.
Participants will be exposed to a controlled dim-light condition of approximately 5 lux during the scheduled overnight sleep episode. This condition will serve as the comparator for the artificial-light-at-night condition of approximately 100 lux.
Wake After Sleep Onset
Wake After Sleep Onset (WASO) is a measure of sleep fragmentation. Participants complete a daily diary each morning for a week where they report how many minutes they think they were awake the previous night after first falling asleep. Nightly WASO collected over 1 week immediately preceding each timepoint are averaged. Higher WASO indicates more sleep disruption.
Time frame: Baseline and 2 weeks (end of intervention)
Number of lapses on the Psychomotor Vigilance Test
Number of lapses recorded during the 10-minute Psychomotor Vigilance Test (PVT) is a measure of neurobehavioral alertness. A lapse on the PVT is a response to stimulus \>500 msec. A higher number of lapses indicates lower vigilance and greater neurobehavioral impairment.
Time frame: Baseline and 2 weeks (end of intervention)
Karolinska Sleepiness Scale
The Karolinska Sleepiness Scale (KSS) is a measure of self-reported sleepiness, a one-item scale from 1 (very alert) to 9 (sleepy; great effort to keep awake).
Time frame: Baseline and 2 weeks (end of intervention)
Resting state stress visual analog scale
Self-reported resting state stress is measured using a one-item visual analog scale (VAS) from 0 (Stressed Out) to 100 (Calm/Relaxed). Participants answer the resting state stress VAS each morning upon wake. Daily scores collected over 1 week immediately preceding each timepoint are averaged
Time frame: Baseline and 2 weeks (end of intervention)
Change in cortisol
Change in cortisol before and after a 20-minute stress task is measured using salivary biosamples.
Time frame: 2 weeks (end of intervention)
Multi-day learning curve composite score
Cognitive function is measured with a multi-day learning curve composite score based on a cognitive assessment that participants complete daily over 1 week preceding the timepoint. The composite score ranges from 0 (no learning) to 1 (optimal learning).
Time frame: 2 weeks (end of intervention)
Patient-Reported Outcomes Measurement Information System-Depression Scale
The Patient-Reported Outcomes Measurement Information System-Depression Scale (PROMIS-D) is a self-report short-form to assess depressive symptoms. A higher score indicates more depressive symptoms.
Time frame: Baseline and 2 weeks (end of intervention)
WHODAS 2.0 daily functioning score
The World Health Organization Disability Assessment Schedule (WHODAS) 2.0 is a 36-item self-report questionnaire to assess daily functioning. The score ranges from 0 (no disability) to 100 (full disability).
Time frame: Baseline and 2 weeks (end of intervention)
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