Owl, Lark, or Somewhere In Between: What Are the Different Sleep Types?

Your Internal Clock Controls Your Sleep: Know How It Ticks to Sleep Better and Stay Healthy

We all enjoy sleeping — and hopefully get enough of it. But not everyone knows what type of sleeper they are. Yet this knowledge is important. How we function during the day, when we get tired, and when we should go to bed to wake up refreshed depends on our internal clock. Knowing your sleep type is essential for understanding and optimizing your sleep habits and needs. So, the question is: What’s your chronotype?

The Most Common Type: The Intermediate (or “Mixed”) Type

Broadly speaking, we distinguish between early types, late types, and intermediate types. These three “chronotypes” describe a largely genetically determined preference for certain sleep and wake times within a recurring daily rhythm. However, this rhythm doesn’t run at the exact same length for everyone.

• For early types (so-called “larks”), the internal rhythm is slightly shorter than 24 hours. They tend to get sleepy earlier.

• For late types (“owls”), the rhythm is slightly longer than 24 hours, so they naturally fall asleep later.

The majority of people fall somewhere between the two extremes — they are intermediate types without a strong preference for either early or late bedtimes. But the differences go beyond sleep: chronotypes also differ in terms of organ activity, body temperature, hormone levels, and other physiological processes throughout the day [1, 2].

A Society Designed for Larks

Larks get sleepy earlier and naturally wake up earlier — which fits perfectly with the typical societal schedule. Owls, however, go to bed later and would prefer to sleep in. Unfortunately, society doesn’t adjust for individual chronotypes. School and work often start around 8 a.m., a schedule that favors early types. This puts late chronotypes at a disadvantage.

If you're a night owl who struggles to get going in the morning, morning light exposure can help — for example, by walking to work. Light and movement both activate the body. It's also beneficial to wind down in the evening and avoid stimulating activities. Maintaining a regular wake-up time — even on weekends — can also support a healthier rhythm.

Whatever your chronotype may be, it makes sense to identify your daily peak times and use them for important or demanding tasks. Less demanding tasks and routine work can usually be handled during low-energy periods [4].

sleep² Tips

• Observe yourself: Find out which chronotype you belong to and when during the day you’re most productive and focused.

• Use your peak phases: Tackle demanding tasks during high-energy times and schedule simpler or repetitive tasks for your low-energy phases. If needed, take a break or do a relaxation exercise — you’ll bounce back with renewed energy.

• Use daylight: Adjust your internal clock by getting outside during the day and aim to stick to a consistent sleep schedule.

References:

1. Merrow, M., Spoelstra, K., and Roenneberg, T. (2005). The circadian cycle: daily rhythms from behaviour to genes. EMBO reports, 6(10), 930-935.

2. Cajochen, C., Chellappa, S., and Schmidt, C. (2010). What keeps us awake? The role of clocks and hourglasses, light, and melatonin. Int Rev Neurobiol, 93, 57-90.

3. Roenneberg, T. (2012). What is chronotype? Sleep and Biological Rhythms, 10, 75-76.

4. Roenneberg, T., Wirz-Justice, A., and Merrow, M. (2003). Life between clocks: daily temporal patterns of human chronotypes. Journal of Biological Rhythms, 18(1), 80-90.