There are health differences between being a lark that wakes up early, and a night owl that stays up late.
The study found that sleep habits affect our waistline, fertility, pain levels and even cancer risk.
It also affects your personality, with night owls being more likely to demonstrate dark personality traits like narcissism and deceitfulness.
Researchers interviewed more than 200 people about their personalities and sleeping habits, and found that early-rising larks always eat breakfast within half an hour of waking and that gets their metabolism going.
But night owls are more partial to a midnight meals, and are more likely to eat too much and gain weight.
Night owls also tend to be more sleep deprived than early risers, and they are more likely to snore.
** But the news isn't all bad for the late sleepers.
Some studies suggest that early risers are at greater risk of some cancers, particularly breast and colorectal cancer- possibly because of melatonin levels