Does Dark Sleep Environment actually make a difference, or is it overhyped?

Research on night-time light exposure is supported by a large prospective cohort study linking light exposure at night to higher cardiovascular disease incidence, alongside a microlongitudinal study finding night-to-night associations between light exposure and sleep health, and broader reviews on artificial light at night and circadian disruption. Weighing the data: Dark Sleep Environment looks an early-stage, lower-priority area for now — the evidence is only moderate (48/100), and its estimated impact (42/100) is on the lower end too.