Late sleepers (people who go to sleep after midnight and wake up in the mid-to-late morning) not only sleep less than "normal sleepers" (people who fall asleep shortly before midnight, and get up around 8 a.m.), but also seem to consume more dinner calories than "normal sleepers," Dr. Michael Breus explained in this blog post.
Breus wrote:
These habits of late sleepers -- sleeping less, going to sleep later in the night, and eating more after 8 p.m. -- were all found to be associated with a higher body mass index. Among these habits, eating after 8 p.m. was the strongest predictor of a higher BMI. What does this mean? It's not just what you eat, but when you eat, that can affect your ability to lose weight. And your sleep habits can have a significant influence on the timing of your eating, as well as on how much you eat.
In addition, The Washington Post reported in 2005 on a study showing that people who sleep fewer than seven hours a night are more likely to be obese (based on data from 10,000 people ages 32 to 49).