Study from Harvard links obesity to those getting less than five hours of sleep.
The amount of sleep Americans say they get every night has declined from an average of approximately 8.5 hours in the 1960s to slightly less than 7 hours today. There are probably lots of reasons why, but they likely include 24/7 occupations, prolongation of the “day” with artificial lighting, the use of electronic devices at bedtime (blue-wavelength light from these devices delays sleep onset), and the widespread belief that sleep is less of a priority compared to other activities, whether they are work- or pleasure-related.
Not sure I agree with the electronic devices comment at bedtime, mine actually puts me to sleep just as if I was reading a book!
Many studies involving thousands of adults have generally found that those who sleep 5 hours or less per night, but sometimes 6 hours or less, were up to 45% more likely to be obese.
Source: Too little sleep and too much weight: a dangerous duo – Harvard Health Blog – Harvard Health Publications