The varied nature of animal life can be used to illustrate several different sleep styles. The first style—the lark—is a morning bird, your basic get-up-and-go type. If you wake up brimming with energy, sometimes even before the alarm clock rings, you’re a lark. Early to bed, early to rise, larks are well suited to the structure of the 9 to 5 workday.

“Larks tend to be go-getters but they’re not gregarious,” says Michael Smolensky, M.D., co-author of The Body Clock Guide to Better Health, and visiting professor at the University of Texas, “They tend to be introverted and are overall more conscientious and disciplined.”

Sometimes this can cause friction at work, Smolensky notes. “Larks tend to want to get to work early and are highly productive in the morning. This gets people jealous, especially when larks are working with late-risers.”

Women are more likely to be larks than men, at least in Western cultures—and older people become more lark-like as they age.

The lark personality is also more depression-prone than those who are late-risers.