Background: Blue wavelengths are thought to have an effect on circadian rhythms. Using a smartphone, which emits a 453 nm blue light, can worsen the quality of sleep.
Aims: To study the skin changes caused by poor sleep quality induced by smartphone usage.
Methods: The participants were 22 Korean women aged 20-39 years, with no sleep problems and a Pittsburgh Sleep Quality Index (PSQI) score of <5. The participants used a smartphone for 2 h before normal sleep hours. The measurement points were as follows: after a good sleep (D0), after bad sleep day 1 (D1), after bad sleep day 3 (D3), and after bad sleep day 7 (D7). The sleep time, wake-up time, shallow sleep rate, and sleeping time duration were recorded using a smartwatch.
Results: The quality of their sleep deteriorated. The average time of falling asleep extended to 2 a.m., which was about 34 min later. Additionally, their skin moisture content decreased, and sebum content increased. Skin desquamation was increased, and skin gloss, transparency, and elasticity decreased mainly on the skin surface.
Conclusions: Sleep quality decreases with smartphone usage among people who do not usually use their smartphones before going to sleep and do not have any sleep problems. The results showed significant changes in skin optics and surface properties when the quality of sleep was degraded for 7 days.
Keywords: COVID-19; blue light; digital aging; sleep quality; smartphone.
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