Polar Day and Night
At the North Pole, the sun rises around 21 March, sets around 21 September, rises around 21 March, and so on. The long cycle of day and night is caused by the tilt of the earth's axis as the earth orbits the sun.
People of polar regions have adapted themselves to these conditions as well as possible, but the "big-eye," or sleeplessness, is a frequent problem during arctic summers when the sun streams into bedrooms all night long. In winter, people also find it difficult to adjust to perpetual darkness.
Depending on the latitude, polar day begins anywhere from mid-March through mid-May, while polar night begins anywhere from late September through late November.
