biostudies-literatureVethe DNorwegian University of Science and TechnologyEkstrastiftelsen Helse og Rehabiliteringzsaa194https://www.ebi.ac.uk/biostudies/studies/S-EPMC7953207biostudies-literatureUnknown44(3)<h4>Study objectives</h4>Blue-depleted lighting reduces the disruptive effects of evening artificial light on the circadian system in laboratory experiments, but this has not yet been shown in naturalistic settings. The aim of the current study was to test the effects of residing in an evening blue-depleted light environment on melatonin levels, sleep, neurocognitive arousal, sleepiness, and potential side effects.<h4>Methods</h4>The study was undertaken in a new psychiatric hospital unit where dynamic light sources were installed. All light sources in all rooms were blue-depleted in one half of the unit between 06:30 pm and 07:00 am (melanopic lux range: 7-21, melanopic equivalent daylight illuminance [M-EDI] range: 6-19, photopic lux range: 55-124), whereas the other had standard lightinSleepThe evening light environment in hospitals can be designed to produce less disruptive effects on the circadian system and improve sleep.PMC7953207903698002018/FO19876081850077Morken GKjorstad KVethe DSalvesen OVestergaard CLScott JKallestad HSand THeglum HSFaaland PMEngstrom MOlsen ALangsrud KfalseThe evening light environment in hospitals can be designed to produce less disruptive effects on the circadian system and improve sleep.<h4>Study objectives</h4>Blue-depleted lighting reduces the disruptive effects of evening artificial light on the circadian system in laboratory experiments, but this has not yet been shown in naturalistic settings. The aim of the current study was to test the effects of residing in an evening blue-depleted light environment on melatonin levels, sleep, neurocognitive arousal, sleepiness, and potential side effects.<h4>Methods</h4>The study was undertaken in a new psychiatric hospital unit where dynamic light sources were installed. All light sources in all rooms were blue-depleted in one half of the unit between 06:30 pm and 07:00 am (melanopic lux range: 7-21, melanopic equivalent daylight illuminance [M-EDI] range: 6-19, photopic lux range: 55-124), whereas the other had standard lightin2021-01-01T00:00:00Z2021 Mar2025-04-05T13:50:27.136Z2025-04-05T13:50:27.136ZS-EPMC79532073295441210.1093/sleep/zsaa194