The effects of the polar night on humans

Body and mental health: what does the lack of natural light cause for people living in some areas of the Arctic Circle?

by Lorenzo Ciotti
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The effects of the polar night on humans
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The polar night appears to cause very large effects on the human body and can cause depression in many individuals, just as polar days can also affect people.

Those suffering from seasonal emotional disorder are treated with artificial light therapy, as the psychological benefits provided by natural daylight require relatively high levels of ambient light, which are not present during polar twilight.

In the polar circles, the polar night that occurs in conjunction with the dark solstice actually lasts not just 24 hours, but rather just under 48 hours. In the days immediately before and after the solstice, the sun rises above the horizon a few minutes before local noon and sets a few minutes later.

At the solstice, however, this brief parenthesis of the sun above the horizon is missing, thus creating a polar night that begins with the setting of the sun shortly after local noon on the day before the solstice, and ends with the rising of the sun just before noon local of the day following the solstice itself.

Regarding the degree of darkness that is reached during daylight hours in the places where the polar night occurs, it must be kept in mind that in any case the moon is a source of light that also illuminates the territories located between the polar circle and the pole facing outward from the solar system; for this reason, even where the astronomical polar night occurs, the solar darkness will be deeper the closer to black moon periods, and lower the closer to full moon periods.

Polar night
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How many types of polar night are there?

Over the 6 months in which the phenomenon develops, different types of polar night occur, some of which only in the areas closest to the pole; this is in relation to the maximum number of degrees below the horizon that the Sun will reach during daylight hours in the place in question, which depends on the latitude of the place itself.

In fact, based on the latitude of the place it is determined in which period of the semester the Sun will remain below the horizon even during the day, as well as the maximum number of degrees below the horizon that it will gradually reach during this period during daylight hours, number of degrees on which depends the level of darkness in the place in question during the day of the polar night, and therefore the type of polar night that occurs.

The Polar Night occurs over an area that gradually extends, initially coinciding with the pole and then reaching the polar circle, and again reducing to the pole before ceasing, all within the space of 6 months. In the northern hemisphere it occurs between the September and March equinoxes, with its peak extension during the December solstice, when it reaches the Arctic Circle, while in the southern hemisphere it occurs between the March equinox and that of September.