Everyone has a biological clock that governs the rhythm of their day, and not everyone's clock keeps the same time. That's why some people are early birds, and others night owls. But according to sleep specialist and psychologist Michael Breus, PhD, there are more than just larks and owls in this world. 

In his new book The Power of When ($28, amazon.com), Breus argues that the majority of us fall into four categories (which he's named after mammals, not birds) and that knowing your "chronotype" will help you figure out the best time of day to do just about everything—from when to have your first cup of coffee to the ideal time to exercise, have sex, and more.

Below, we pulled a few tips from his book on how to be more productive throughout the day, whether you're a "dolphin," "lion," "bear," or "wolf." Read on to see which chronotype describes you best, and learn how you can tweak your routine so you stay energized longer. (To find out more about your personal chronotype, check out Breus' online quiz.)

If you’re a light sleeper and wake early, but not fully refreshed…

You’re likely a dolphin. Breus named this group of people after the ocean-dwelling mammal because real dolphins only sleep with half their brain at a time. The name is a good fit for folks who are prone to restless sleep and insomnia, he explains. While “dolphins” tend to feel groggy in the a.m., they should exercise first thing, says Breus. Even the sleepiest heads can go from exhausted to pumped after a bout of intense physical activity. His recommendation: After a fitful night, do 100 crunches and 20 push-ups, to raise your blood pressure, body temp, and cortisol levels before you start your day.

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If you rise bright-eyed at dawn, and feel sleepy by mid-afternoon…

You’re likely a lion. Like real lions, people with this chronotype are at their best in the morning; as the day goes on, their energy level takes a dive. Breus suggest scheduling your most important tasks between 10 a.m. and 12 p.m. Mid-morning is “when you are best equipped, hormonally speaking, to make clear, strategic decisions,” he writes. This is also when you'll get hungry, since you've been firing on all cylinders for hours. But a smarter strategy is to snack earlier, around 9 a.m., and wait to eat lunch until after 12. Lions tend to crash an hour or two post-lunch, so it's best to eat later rather than earlier. If you can, eat outside or take a walk on your break; the exposure to sunlight will help you feel more alert.

If you make good use of the snooze button and get tired by late evening…

You’re likely a bear. About half of people fall into this category, named after those diurnal (active in the day, restful at night) creatures known for their long, deep sleeps. People with this chronotype have a sleep/wake pattern that matches up with the solar cycle, says Breus, which is lucky for them. They require a solid eight hours (at least) of quality z's, and often need a few hours to fully wake up. To put a pep in your step in the first part of the day, Breus suggests prioritizing a hearty, high-protein breakfast around 7:30 a.m. “Bears usually reach for high-carb choices like cereal or a bagel,” writes Breus, but “eating carbs in the morning raises calm-bringer serotonin and lowers cortisol levels, which you need to get up and moving.”

RELATED: How to Get More Energy, From Morning to Night

If you don’t get to sleep until midnight or later (and struggle in the mornings)…

You’re likely a wolf. Named for the nocturnal hunters, “wolves” are most alert after the sun has set—typically around 7 p.m., according to Breus. They don’t feel tired until very late at night, and have trouble getting up before 9 a.m. Wolves tend to down several cups of coffee in the morning. But since this is when your “wake-up” hormones are flowing, you'll get more bang for your buck if you wait until “your morning cortisol release has run its course,” says Breus. Around 11 a.m. is when a cup of joe will do you the most good. And take it black. Sugar and cream could cause a spike in blood sugar and insulin that may slow you down more.

Another tip: Bathing in the evening rather than the morning could help you nod off at a more reasonable hour. When you get out of a hot shower or warm bath, your core body temperature drops, he writes, “signaling to the brain to release melatonin, the key that starts the engine of sleep.”