LED lighting effect on sleep, sleepiness, mood and vigor

Several scientific studies indicate that blue light exposure at night reduces the melatonin secretion, improving vigilance and diminishing sleepiness; moreover has been demonstrated that a blue light dose administered in the evening has a positive effect for shift workers. In this study the effect of cool LED lighting exposure during daily hours has been investigated in two experiments: self-reported sleep, sleepiness, mood and physical vigor have been assessed prior and post light exposure using bipolar scales (KSS and GVAS) and sleep diary. In the first investigation (E1) the experimental light condition consisted in a 4000 K LED light and the control condition was the halogen lighting (2800 K); while in the experiment 2 (E2) a 6800 K LED lighting has been compared with a warm 3000 K LED light condition. In both experimental studies the cool light exposure duration was about 1 hour. Results of E1 indicated that the experimental light condition had a positive effect on night sleep latency; in E2 shorter awakenings and longer sleep time have been observed for participants exposed to cool LED lighting.