Blocking Short-Wavelength Component of the Visible Light Emitted by Smartphones' Screens Improves Human Sleep Quality.

Background: It has been shown that short-wavelength blue component of the visible light spectrum can alter the circadian rhythm and suppress the level of melatonin hormone. The short-wavelength light emitted by smartphones' screens can affect the sleep quality of the people who use these devices at night through suppression of melatonin.

Objectives: In this study, we examined the effects of covering the screens of smartphones with different filters (changing the effective wavelength of the light) on sleep delay time in 43 healthy students.