When are there extreme days and nights in the polar regions?

In the Arctic, there is an extreme day phenomenon from the vernal equinox to the autumnal equinox, and the extreme day phenomenon from the vernal equinox to the summer solstice will gradually expand from the Arctic, and the area where the extreme day phenomenon occurs from the summer solstice to the autumnal equinox will gradually decrease. There is polar night phenomenon from vernal equinox to autumnal equinox in Antarctica, and the phenomenon from vernal equinox to summer solstice gradually expands from Antarctica, and the area where polar night phenomenon appears from summer solstice to autumnal equinox gradually decreases.