Not only is it the end of the Mayan calendar today, today is also the winter solstice! The annual astronomical event marks the shortest day of the year, and the official start of winter. In honor of the longest night of 2012, we put together a list of our five favorite overnight products that go to work while you sleep. Unless you have any post-Mayan apocalypse parties to attend, turn in early to let these skin serums, hair masks, and DIY facials do overtime so that you wake up to a brighter complexion and healthier strands. Click through our gallery to shop our five favorites!