Quick Answer: A chronotype is your body's natural preference for when to sleep, wake and feel most alert. It is partly genetic and also shifts with age and light exposure. Take our free Chronotype Quiz to identify your sleep animal: Lion (early bird), Bear (solar rhythm), Wolf (night owl), or Dolphin (light sleeper).
Your chronotype is more than just being a morning person or a night owl. It is the internal timing that governs your body's natural preference for sleep and wakefulness. It is partly genetic: hundreds of gene variants have been linked to it, PER3 among them, and it also shifts with age and light exposure. Teenagers and young adults tend to run later, and most people drift earlier as they get older.
The four-animal model was popularised by sleep psychologist Dr. Michael Breus in The Power of When. It's a practical framework built on morningness–eveningness research, not a clinical diagnosis. Breus estimates that roughly 15 percent of people are Lions, about half are Bears, 15 to 20 percent are Wolves and around 10 percent are Dolphins.
1. The Lion (The Early Bird)#
Lions are the classic morning people. They wake up naturally with the sunrise, often feeling a surge of energy and mental clarity. They hit their peak productivity before noon and usually experience a significant dip in energy by the late afternoon. For a Lion, the evening is a time for winding down. They typically fade early in the evening and feel best with a consistent early bedtime. More on the Lion chronotype.
2. The Bear (The Solar Rhythm)#
Bears are the most common chronotype. Their energy levels follow the sun closely. They work best in the mid-morning and experience a typical post-lunch dip between 2 PM and 4 PM. Bears are generally easygoing and have a high sleep drive, meaning they need a solid eight hours of sleep to function at their best. More on the Bear chronotype.
3. The Wolf (The Night Owl)#
Wolves struggle significantly in the morning. They find their stride late in the afternoon and evening. While the rest of the world is winding down, Wolves are often at their most creative and energetic. This can lead to a conflict with traditional 9 to 5 work schedules, a phenomenon known as social jetlag. Struggling at 7 AM isn't a discipline problem; a Wolf's body clock is simply running later. More on the Wolf chronotype.
4. The Dolphin (The Light Sleeper)#
Dolphins are sensitive sleepers who often struggle with insomnia. They have a very high level of alertness even when they are tired. Their peak focus occurs in the mid-afternoon, but they may feel wired throughout the day. Because their brains are often "on," they benefit from a deliberate wind-down routine that tells the body it is safe to sleep. If you regularly can't fall or stay asleep, talk to a doctor; CBT-I is the first-line treatment for chronic insomnia. More on the Dolphin chronotype.
ARC starts your day from your chronotype, which moves where your light window, peak, dip and caffeine cutoff fall. After about ten days of one-tap energy check-ins it measures when your dip really lands and corrects the window if your animal guessed wrong.
Identifying your chronotype is the first step toward syncing your schedule with your biology. When you stop fighting your natural rhythm, the day tends to feel less like a fight.