I’m not quite sure of the causal link between [inadequate] sleep and obesity; but I do know that when I’m not as well rested from a night’s sleep, I have a lower resolve, similar to being under the influence of alcohol. This increases my appetite and leads to bigger food binges.
There’s a saying that every hour of sleep before midnight is worth two past midnight. I’ve experienced this enough to know that it’s true. After all, why do you think it’s called “mid-night”? Notice that it gets dark around 8 PM. It should be “lights out” at this time, but we’re so used to turning the lights on. I also notice that if I’m watching TV or a movie, I’ll get naturally sleepy around 10 or 11 PM; but the stimulation is enough to keep me awake. And if I eat a snack late at night, it interferes with my sleep (due to the work of food being digested).
Notice your pets. They sleep most of the day and wake up only when you have food or they want to play. And they are very active.
One last tip: one of the best ways to encourage adequate sleep is to exercise hard on a regular basis. Your bed will never feel so good.