Hibernation in July

Do humans hibernate?? I know I suffer from lack of energy and excessive sleepiness in the middle of winter. Even though the days are lengthening and sunshine occurs most days, winter is always the time of year I feel most unsettled, cloudy of mind and generally weary.
Mind you, school holidays are always difficult as the library gets very busy during the day. The shelves are relatively bare of children's books and DVD's (both kids and adults). The computers show Halo or Runescape monsters flickering on their screens. Tuesday and Wednesday was around the full moon so it also seemed that the customers also were fractious and rude.
As work is busy, so too is the "life" outside with transporting teenagers to and from each others houses, movie theatres or moving bikes on car to various places.
During most school holidays I get another visitor as well - an elderly relation comes to stay so I have a chance to see what will happen to me when I get older! Its enough to drive oneself into a decline.
Fortunately my garden is showing signs of renewal with the first of the magnolia buds flowering on naked branches. The citrus trees are producing abundantly, a good sign given how hot it was in summer. So now I can have fresh limes, tangelos, lemons and lemonades to add to my winter diet. The water tanks are full, giving optimism for the next scorching summerwhich will be here before I know it. Melbourne has such extremes of climate!