Blått lys forbedrer prestasjon men ikke subjektiv årvåkenhet og døgnrytme i løpet av tre simulerte nattskift

Det er økende interesse for den aktiverende effekten ved bruk av blått lys, men det er få studier som har vurdert effekten av slikt lys under nattarbeid. Forskere fra Universitetet i Bergen, Nasjonal kompetansetjeneste for søvnsykdommer, University of Surrey og North-West University har i denne studien med et «counterbalanced crossover design» undersøkt effekten av et standard polykromatisk blått lys (7000 K; ~ 200 lx) sammenlignet med et varmt hvitt lys (2500 K), i tre påfølgende simulerte nattevakter. Totalt 30 friske deltakere ble inkludert i studien. Deltakerne opplevde 7000 K som mer egnet for arbeid, men vurderte likevel 2500 K lys som mer behagelig. Dataene tyder på mindre, men gunstige effekter av 7000 K lys sammenlignet med 2500 K lys på prestasjon under nattarbeid. Det var ikke forskjell på adaptering av døgnrytmen mellom de ulike lysforholdene, men forskerne konkluderer at disse funnene må tolkes med forsiktighet. Feltstudier vil være nødvendig for å undersøke lignende lysintervensjoner i virkelige omgivelser for å utarbeide anbefalinger angående belysning for nattarbeidere.

Blue-Enriched White Light Improves Performance but Not Subjective Alertness and Circadian Adaptation During Three Consecutive Simulated Night Shifts

Erlend Sunde, Torhild Pedersen, Jelena Mrdalj, Eirunn Thun, Janne Grønli, Anette Harris, Bjørn Bjorvatn, Siri Waage, Debra J. Skene, Ståle Pallesen

Studien er publisert i Frontiers

Use of blue-enriched light has received increasing interest regarding its activating and performance sustaining effects. However, studies assessing effects of such light during night work are few, and novel strategies for lighting using light emitting diode (LED) technology need to be researched. In a counterbalanced crossover design, we investigated the effects of a standard polychromatic blue-enriched white light (7000 K; ∼200 lx) compared to a warm white light (2500 K), of similar photon density (∼1.6 × 1014 photons/cm2/s), during three consecutive simulated night shifts. A total of 30 healthy participants [10 males, mean age 23.3 (SD = 2.9) years] were included in the study. Dependent variables comprised subjective alertness using the Karolinska Sleepiness Scale, a psychomotor vigilance task (PVT) and a digit symbol substitution test (DSST), all administered at five time points throughout each night shift. We also assessed dim-light melatonin onset (DLMO) before and after the night shifts, as well as participants' opinion of the light conditions. Subjective alertness and performance on the PVT and DSST deteriorated during the night shifts, but 7000 K light was more beneficial for performance, mainly in terms of fewer errors on the PVT, at the end of the first- and second- night shift, compared to 2500 K light. Blue-enriched light only had a minor impact on PVT response times (RTs), as only the fastest 10% of the RTs were significantly improved in 7000 K compared to 2500 K light. In both 7000 and 2500 K light, the DLMO was delayed in those participants with valid assessment of this parameter [n = 20 (69.0%) in 7000 K light, n = 22 (78.6%) in 2500 K light], with a mean of 2:34 (SE = 0:14) and 2:12 (SE = 0:14) hours, respectively, which was not significantly different between the light conditions. Both light conditions were positively rated, although participants found 7000 K to be more suitable for work yet evaluated 2500 K light as more pleasant. The data indicate minor, but beneficial, effects of 7000 K light compared to 2500 K light on performance during night work. Circadian adaptation did not differ significantly between light conditions, though caution should be taken when interpreting these findings due to missing data. Field studies are needed to investigate similar light interventions in real-life settings, to develop recommendations regarding illumination for night workers.