Chronic sleep restriction (SR) has detrimental influences on cognitive functions. Although such effects can be reduced by light exposure, it is necessary to find out if naturalistic light conditions such as dawn simulating light can promote daytime cognitive functions continuously (Gabel et al., 2014).
In a recent 24-hour balanced cross-over study, 17 participants joined the study after having the SR with 6 hours of sleep (Gabel et al., 2014). The participants were exposed to two different light settings each morning, one was dawn simulating light (DSL), the other was control dim light (DL). During the planned wakefulness period, the participants completed cognitive tests every 2 hours and questionnaires hourly for mood evaluation.
The study found that the “light condition” had effects on several cognitive performances including the motor tracking task, continued attention to response task, as well as the working memory task (Gabel et al., 2014). In addition, the first group subjects (DSL) also had superior performance in the Simple Reaction Time Task during the day following the morning simulating light exposure.
The study also found that the light exposure had greater effects among the low performers than in the high performers (Gabel et al., 2014). However, no significant influences were discovered for concentration and motivation.
This study showed that artificial morning light exposure may be very helpful for improving cognitive performance among those with mild SR (Gabel et al., 2014). However, such effects were domain-specific and no physiological effects were assessed. More studies among larger group of population are still needed to identify the effects and mechanisms of the artificial morning light exposure on both psychological and physiological aspects.
Gabel V, Maire M, Reichert CF, Chellappa SL, Schmidt C, Hommes V, Cajochen C, Viola AU. Dawn simulation light impacts on different cognitive domains under sleep restriction. Behav Brain Res. 2014 Dec 27. pii: S0166-4328(14)00846-8. doi: 10.1016/j.bbr.2014.12.043.