The impact of blue-light inhibition on melatonin suppression and sleep architecturePosted: January 6, 2015
Elie Gottlieb (2014, from ResearchGate: https://rollins.academia.edu/ElieGottlieb)
Blue light, such as the light emitted from home computers and tablets, has been shown to suppress melatonin, thereby increasing sleep latencies and phase delaying sleep/wake rhythms (Figueiro, Plitnick, & Rea, 2012). The rise of endogenous melatonin at night is associated withincreased sleepiness. Evening exposures to certain light levels and spectra will diminish melatonin production (Figuerio et al., 2012; Lewy & Sack, 1996). Studies using amber lens glasses compared to placebo lens glasses have demonstrated that blocking blue light improves subjective sleep quality (Wood, Rea, Plitnick, Figueiro, 2013; Burkhart & Phelps, 2009). The purpose of the present study was to determine whether the use of a free (no-cost) blue-light blocking computer application would result in similar but objectively measured shorter sleep latencies and improved sleep/wake rhythms. Participants were recruited using e-mail offers and respondents were interviewed to determine further eligibility. A 3-day sleep diary was completed to determine average evening computer use time and average bed and rising times. Participants were provided with a computer/tablet application (F.Lux), which functions to block blue-light from electronic devices. Objective sleep parameters were measured using a fitted wrist-accelerometer. Subjective sleep parameters were measured using daily sleep diaries. Participants were randomly assigned to either condition one (F.Lux/no F.Lux, placebo lens glasses), or condition two (F.Lux/noF.Lux, amber lens glasses). Each condition was conducted over a period of six weeknights and each separated by a minimum 1-week period. Condition one-week one: participants were instructed to enable the F.Lux application set to full blue-light block mode on their electronic device 3-hours prior to lights out and to put on the placebo lens glasses. Immediately prior to lights out, participants were instructed to activate “Sleep” mode on the wrist-accelerometer and then to remove the glasses. Upon awakening, participants were instructed to activate “Awake” mode on their accelerometer. Condition one-week two: instructions for week two were identical to week one with one exception, participants were instructed to enable the F.Lux set to zero blue-light block mode on their electronic device 3-hours prior to lights out. Both weeks of condition two followed the same protocol as condition one but amber glasses were worn. On the third day of each condition week the wristband,glasses, and sleep diaries were collected. Data was analyzed using a 2×2 mixed-model ANOVA with glasses (clear versus amber) as the between subjects factor and F.Lux (off versus on) as the within subjects factor. There was a significant difference in self-reported sleep latencies between F.Lux on (M= 28.14, SD= 24.69) and F.Lux off conditions, with participants reporting shorter sleep latencies following F.Lux on (M= 18.26, SD= 15.45), F(1, 5) = 10.22, p= .02, ƞ2 = .67.The analysis of the accelerometer data indicated a marginally significant effect for F.Lux, F(1, 5)= 5.71, p= .06, ƞ2= .53 that was qualified by a marginally significant glasses by F.Lux interaction, F(1, 5) = 5.52, p= .07, ƞ2= .53; there was a marginal difference for lens when the F.Lux was off (Clear: M= 28.44, SD=14.78; Amber: M=16.42, SD=9.20) which diminished to almost no difference when F.Lux was on (Clear: M= 18.22, SD= 10.84; Amber: M= 16.33, SD= 8.59). This interaction was primarily due to the longer sleep latencies in the clear/F.Lux off condition. The use of blue light blocking filters may be recommended for use with blue light emitting electronic devices in the hours prior to sleep to facilitate shorter sleep latencies and to normalize sleep/wake rhythms. Additional data collection is currently in process.