Abstract

Overview

This study explores the immediate impact of smartphone use in the evenings, specifically analyzing the effects of blue light emitted by Light Emitting Diode (LED) displays. The research focuses on several health parameters including sleep and mood disturbances.

Findings

• Conducted with a double-blind, randomized, cross-over, placebo-controlled design over two 3-day admissions per participant.
• Participants used smartphones with conventional LED or suppressed blue light from 7:30 PM to 10:00 PM (150 minutes).
• Key physiological measures such as serum melatonin and cortisol levels, and body temperature were monitored, alongside psychiatric measures.
• Significant findings include a decrease in sleepiness and confusion among users of blue light smartphones but an increase in commission errors.
• Notably, blue light exposure prolonged the time to melatonin onset and slightly increased body temperature and serum melatonin levels, though these changes were not statistically significant.

Conclusion

Exposure to blue light from smartphones in the evening negatively affects sleep and cognitive functions, demonstrating particular sensitivity in these areas compared to physiological changes.