The body functions best when well rested. When you don't get enough sleep, your body experiences physiological stress and, biochemically, you store fat more efficiently. When you're tired, you also don't handle stress as well, so you may reach for food as a coping mechanism. Further, you may be taking in extra calories from late-night snacking. Some people think eating might help them get back to sleep, but all it really does is add more calories to their daily total.
Symptoms that you may not be getting enough rest include fatigue, low energy levels, nodding off easily, and feeling irritable. When you develop good sleeping rituals and get regular exercise, you sleep better. So.... try to get more hours of sleep each night.