Sleep is a very important part of our life. If you are not sleeping well, you are preventing your body from repairing itself. When you sleep soundly, your body gets an opportunity to repair the wear and tear caused during the day. The body uses genetic information and metabolizes the protein to rebuild damaged muscles and components.
Sleep is even more important when you start sustained physical activity or hitting the gym regularly. If you do not sleep well, not only is the repair incomplete but also it seems to make your body put on weight.
Change the direction of your bed, try to make your bedroom as dark as possible at night and get regular exposure to sunshine in order to get your sleep cycle back in order. If that does not work, seek professional help.