Do you sleep like a bear, dolphin, lion or wolf?

According to Michael Breus, a sleep specialist and author of the new book “The Power of When,” there’s a reason why our daily activities and sleep habits vary—our biological clocks tick differently. To help understand these variations, he categorizes four chronotypes, or classifications, based on our routines and then matches them with the mammal whose sleep patterns most closely match our own.

1. You are a bear if:

You need a full eight hours of sleep, waking up at 7 a.m. and going to bed at 11 p.m. You should tackle your most difficult work projects between 10 a.m. and noon, and your best brainstorming time is 8 to 10 p.m.

2. You are a dolphin if:

You are a light sleeper and often suffer from insomnia. You typically are up by 6:30 a.m. and hit the sack around 11:30 p.m. You are most productive with creative projects in the morning, between 10 a.m. and noon. Late afternoons are the best time to take on intellectually challenging tasks.

3. You are a lion if:

You are the most energized in the early morning, rising about 5:30 a.m. Afternoons are the best time for brainstorming. By the end of the day you are exhausted; it’s usually lights out about 10:30 p.m.

4. You are a wolf if:

You are not much of a morning person, struggling to get up by 7 or 7:30 a.m. You are most active and productive in the late afternoon and early evening. You rarely fall asleep before midnight.