If you tried diet and exercise and you still gain pounds, ask yourself whether you are sleeping enough. Swedish researchers studied the effect of sleep deprivation on the brain and found that one area responsible for our reaction to food became more active after a sleepless night: http://www.sciencedaily.com/releases/2012/01/120118111740.htm
An Australian/ New Zealand study about sleep in seven year old school kids found a link between too little sleep and obesity. The 519 children in the study slept an average of 10 hours per night. Those, who got less than 9 hours of sleep, were significantly more likely than the others to be overweight or obese. They were also at a higher risk for mood swings. The study is published in the Journal Sleep. (www.sleepjournal.org
Another study published several months ago found a similar link between sleep duration and body weight for adults. It seems that more time being awake translates to more time spent eating.
So, for those of us with a New Year resolution to sleep more, there is a new pro argument: sleep instead of diet. Works for me!