If you're not getting enough sleep, your metabolism is out of kilter, and you'll gain weight. This article Want to lose weight? Sleep more says:

Sleep and insulin choreograph the dance between leptin, which tells the brain there's no need for food, and ghrelin, which tells the brain it's chow time.

So if you cheat yourself of sleep you're confusing your body, and your appetite increases.

How much sleep do you need? If you're trying to lose weight, do yourself a favor and make sure that you get the complete eight hours that experts suggest.

If you have trouble sleeping, it's worthwhile to get some medical advice.

Discover how to boost your metabolism - sleep, exercise and food will keep your metabolism high.