Daytime melatonin and light independently affect human alertness and body temperature

This study explored the combined effects of daytime melatonin administration and bright light exposure on alertness and body temperature. Melatonin increased sleepiness and altered thermoregulation, raising distal skin temperature. Bright light exposure, however, failed to counter melatonin-induced sleepiness or improve performance but did impact body temperature by increasing proximal and core temperature. These findings suggest melatonin regulates alertness and thermoregulation independently of light's effects, emphasizing the complexity of their interaction.

For improved alertness and thermoregulation, align daytime melatonin use with appropriate light exposure, ensuring doses and timing suit individual needs. Use natural light to maintain circadian rhythms. Evidence suggests limitations in light’s ability to counter melatonin-induced sleepiness, so tailored strategies are key.