The Effects of Pre-bedtime Blue-Light Exposure on Subjective Sleep Quality, Attention, and Work Efficiency in Men Students: A Pilot Study

Although exposure to blue light in the evening has been shown to affect sleep, its effects on alertness and work efficiency the next day are not fully understood.

This study aimed to investigate the effects of pre-bedtime blue-light exposure on subjective sleep quality, attention, and work efficiency.

Thirteen young men (aged 20–23 years) without sleep disorders participated in two sessions, in which they were exposed to either incandescent light or blue light 1 h before bedtime. On the next morning, participants underwent assessments of subjective sleep quality, attention, and work efficiency. Objective parameters during sleep were measured using a mat-type sleep meter (sleep scan, SL- 504; TANITA Corp., Japan).

Blue-light exposure significantly decreased the ratio of time spent in deep sleep (p < 0.05), reaction times (i.e., attention) during the second half of the 10-min session (p < 0.01), and work efficiency (p < 0.05).

The present study suggests that blue-light exposure before bedtime leads to a decrease in the ratio of deep sleep and negative effects on sustained attention and work efficiency.