The skin properties can be influenced by changing altitude because different altitudes have different environments such as air temperature, humidity, UV radiation, and so on, and it is also necessary to investigate the factors which can influence with perceived skin condition such as skin type and skin concerning.

The skin is the outermost layer of the body and is exposed to various environmental conditions, and skin characteristics change along with the environmental conditions. Several studies evaluating variations in skin characteristics have attributed ultraviolet light and external humidity as the factors responsible for skin changes. Skin conditions vary considerably with drastic changes in humidity. Moisture in the skin decreases in an environment that changes from 70% humidity to 40% humidity. 1 There are also reports of a decrease in transepidermal water loss (TEWL) in those who work at low temperatures. 2 We are increasingly exposed to various environments, some of which have never existed before, such as fine dust, face cover/masks due to coronavirus disease (COVID-19) epidemic, and lack of sleep. It is worth noting that the number of studies related to sleep is increasing day by day. Some have reported changes in biophysical properties of skin, such as facial pore size, skin tone, skin hydration, elasticity, desquamation, translucency, and blood flow after constant sleep deprivation. 3 In addition, studies have shown that reduction of sleep from 8 to 4 h, even for 6 days, reduces elasticity and leads to skin aging. 4

Exposure to blue light derives from a variety of technologies, including computers, smartphones, televisions, and light-emitting diodes (LEDs); furthermore, sunlight contains a considerable amount of blue radiation. 1,2 Blue light from everyday electronic devices (eg, smartphones and tablet computers) is rich in short-wavelength light with peaks at 452-456 nm. 2 Blue light exists everywhere in daily life, but

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