Påvirkning av lysintensitet ved simulert nattarbeid.

Forskere fra Universitetet i Bergen og Nasjonal kompetansetjeneste for søvnsykdommer har i denne studien undersøkt hvordan takmontert LEDlys –med varierende lysstyrke, påvirket årvåkenhet og kognitiv prestasjon under tre påfølgende simulerte nattskift, og døgnrytmen etter nattskiftene. 24 deltakere (20 kvinner) jobbet tre påfølgende nattskift (23:00-07:00) under et fullspektrum (4000 K) sterkt lys (900 lux) og et standardlys (90 lux) i en randomisert kontrollert kryssdesign studie med 4 uker mellom betingelsene. De simulerte nattskiftene ble gjennomført på et laboratorium mens deltakerne sov hjemme mellom nattskiftene. Subjektiv årvåkenhet og kognitiv prestasjon ble dårligere i løpet av nattskift under begge lysbetingelsene. Sterkt lys forbedret ytelse og våkenhet under simulerte nattskift og forbedret tilpasning til nattarbeid. Sterkt lys fra takmonterte LED-armaturer har potensial til å forbedre tilpasningen til nattarbeid og redusere risikoen for ulykker og personskader hos nattarbeidere.

Role of nocturnal light intensity on adaptation to three consecutive night shifts: a counterbalanced crossover study.

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

Publisert i Occupational Environmental Medicine

OBJECTIVES: To investigate how a standard ceiling mounted light-emitting diode (LED)-based bright light intervention affected alertness and neurobehavioural performance during three consecutive simulated night shifts, and timing of circadian rhythm after the shifts.
METHODS: Twenty seven participants (20 females, 21.4±2.1 years; mean±SD) worked three consecutive night shifts (23:00-07:00) under a full-spectrum (4000 K) bright light (900 lx) and a standard light (90 lx) condition in a counterbalanced crossover design (separated by 4 weeks). Subjective alertness (Karolinska Sleepiness Scale) and neurobehavioural performance (Psychomotor Vigilance Task and Digit Symbol Substitution Test) were assessed five times during each shift. Salivary dim-light melatonin onset (DLMO) was assessed before and after the shifts. The simulated night shifts were conducted in a laboratory while the participants slept at home.
RESULTS: Subjective alertness and neurobehavioural performance deteriorated during the night shifts in both light conditions. However, bright light significantly reduced alertness and performance decrements as compared with standard light. For a subset of the participants, DLMO was delayed by a mean of 3:17±0:23 (mean±SEM) hours after three night shifts in bright light and by 2:06±0:15 hours in standard light, indicating that bright light causes larger phase delay.
CONCLUSION: Bright light improved performance and alertness during simulated night shifts and improved adaptation to night work. Bright light administered by ceiling mounted LED luminaires has the potential to improve adaptation to night work and reduce the risk of accidents and injuries among night workers.