Impact of Artificial Light at Night on Cognition, Stress, and Sleep in Midlife Women with Vasomotor Symptoms

The broad goal of Project B of the Brigham/Harvard Reproductive Outcomes of Stress and Aging (ROSA) SCORE is to advance the health of midlife women by determining the causal role of vasomotor symptom (VMS)-precipitated exposure to artificial light at night (ALAN) on cognition, mood, daily activity, stress, and sleep. VMS are the most common symptoms during and after menopause, occurring in up to 85% of women, lasting up to 9.0 years on average, and persisting for 10 years or more in 33-40% of postmenopausal women. Sleep disturbance is the most common consequence of VMS, reported by up to 60% of women during and after menopause. Nighttime VMS (or night sweats) commonly disturb sleep by fragmenting it throughout the night. ALAN exposure also promotes wakefulness and fragments sleep, and thus ALAN exposure precipitated by VMS can worsen sleep fragmentation further in midlife women. Investigations of modifiable risk factors for sleep fragmentation in midlife women, such as ALAN exposure, have important public health significance due to the high prevalence of VMS and adverse health correlates of disturbed sleep, including mood disturbance and cognitive decline. Poor sleep during midlife increases the risk of developing dementia by ~30%, underscoring the importance of elucidating the causal impacts of ALAN on cognitive and neuropsychological outcomes in midlife women. We propose a novel conceptualization of ALAN exposure in midlife women with VMS as a chronic stressor leading to cognitive, mood, and daily impairment. Project B will innovatively utilize the robust methodology of a randomized controlled trial of standardized ALAN at two different intensities (physiologically active typical indoor-intensity ~100-lux vs a control physiologically inert dim-light <3-lux) to investigate the causal role of ALAN exposure in changes in (Aim 1) sleep and neurobehavioral alertness; (Aim 2) stress and stress responsivity; and (Aim 3) cognition (including memory), mood, and daily activities in women with VMS. Project B is highly integrated within the ROSA SCORE, enrolling participants from the Project A cohort, examining neurocognitive outcomes in parallel with both Project A and Project C, utilizing sleep and light exposure metrics obtained in collaboration with the Sleep and Light Resource Core, and mentoring and teaching junior faculty and trainees through the Career Enhancement Core. Building on the science and success of our initial funding period and leveraging synergistic SCORE and extensive Brigham/Harvard institutional resources, Project B will make major contributions to the health of aging women by identifying modifiable factors linked to VMS, and findings have a strong potential to inform novel treatment strategies to improve sleep and with downstream implications for dementia susceptibility in aging women.