Are you feeling lethargic, sleepy more than usual now a days.  It might be more serious than you think. You could be suffering from seasonal affective disorder also known as SAD. Behaviors like low energy, losing interest in things you normally enjoy, or wanting more sleep are all signs of depression, could be seasonal affective disorder. 

SAD usually begins in winter but may occur during any season or during change in season. SAD is seen more in population living far from equator towards north or South Pole, but the prevalence varied across ethnic groups. Around 80% of SAD sufferers are women, particularly those in early adulthood. The reason for SAD is basically due to change in circadian rhythm as the day and night length changes. In winters particularly the days are short and nights are long, which causes little exposure of daylight during day time. It is hypothesized that Vitamin D supplements help in overcoming the symptoms.  Taking SAD in other way round, thousand years ago winters used to be a relaxing periods, but now in 24 hour society one is needed to be active every day. Today also some animals hibernate during cold winters, in humans this SAD might be sign of hibernation. But the cause is not known exactly, so is the treatment. Light therapy sometimes helps, a bright light for few hours a day help to decrease the SAD symptoms. Keeping an active social life is also important because if you're not going out in the evenings, staying inside and doing nothing, you're signaling to your body that it should shut down for the winter and it shuts down mentally as well. Doing exercise and taking less carbohydrates is what all can help. A cup of hot chocolate, or a hot coffee is however beneficial to kick the symptoms away.