SLEEP – DAWN SIMULATION


2 RESEARCH ARTICLES


EFFECTS OF DAWN SIMULATION ON MARKERS OF SLEEP INERTIA AND POST-WAKING PERFORMANCE – 2014


Andrew Thompson, Helen Jones, Warren Gregson, Greg Atkinson
METHODS
– 8 participants, who reported difficulty with morning waking:
(1) control (C)
(2) dawn simulation (DS) trial (starting 30 min prior to waking)
RESULTS
(1) After waking in DS, perceived sleep quality was 1.16 ± 0.89 points higher compared with C
(2) Ratings of alertness were significantly higher in DS than C throughout the testing period
(3) Cognitive performance improved in both trials as time awake increased
(4) On average, participants completed a greater number of additions in DS compared with C
(5) Reaction times were also faster in DS compared with C
(6) The self-paced time-trial was completed 21.4 s (4.7 %) quicker in DS
CONCLUSION
– Light exposure during the last 30 min of habitual sleep can increase subjective alertness and improve both cognitive and physical performance after waking


EFFECTS OF ARTIFICIAL DAWN AND MORNING BLUE LIGHT ON DAYTIME PERFORMANCE, WELL-BEING, CORTISOL AND MELATONIN LEVELS – 2013


Gabel V1, Maire M, Reichert CF, Chellappa SL, Schmidt C, Hommes V, Viola AU, Cajochen C.
PURPOSE
– Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and mood
– We investigated the role of morning light exposure as a countermeasure for impaired cognitive performance and mood under sleep restriction (SR)
METHOD
– 17 participants; 48h laboratory protocol, during which 3 different light settings (separated by 2 wks) were administered each morning after two 6-h sleep restriction nights:
(1) Blue monochromatic LED (light-emitting diode) light condition (BL; 100 lux at 470 nm for 20 min) starting 2 h after scheduled wake-up time
(2) Dawn-simulating light (DsL) 30 min before and ending 20 min after scheduled wake-up time (polychromatic light gradually increasing from 0 to 250 lux)
(3) Dim light (DL) condition for 2 h beginning upon scheduled wake time (<8 lux).
RESULTS
(1) Following the first SR, analysis of the time course of cognitive performance during scheduled wakefulness indicated a decrease following DL, whereas it remained stable following BL and significantly improved after DsL
(2) Cognitive performance levels during the second day after SR were not significantly affected by the different light conditions
(3) Ater both SR nights, mood and well-being were significantly enhanced after exposure to morning DsL compared with DL and BL
(4) Melatonin onset occurred earlier after morning BL exposure, than after morning DsL and DL
(5) Salivary cortisol levels were higher at wake-up time after DsL compared with BL and DL


 

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