Assuming you get the recommended seven to nine hours of sleep every night, does it really matter which hours you’re sleeping? The answer seems to be yes—although more research may be needed to determine exactly why. Here’s a look at the difference between the two major sleeping patterns, the research on their health impacts, and how you can nudge your own habits into an alignment that will let you enjoy a healthier, better-rested life.
Larks and owls
A chronotype is how a person lives out their unique propensity to be asleep or awake at certain times of the day, which seems to be genetically determined.1 Understanding yours might help you plan your daily activities to use your time most effectively.
Researchers consider sleeping patterns to fall on a continuum from the early-to-bed, early-to-rise “larks” to the late-to-bed, late-to rise “owls.” Many studies define larks as people who go to bed before 11 p.m. and awaken before 8 a.m., and owls as people who go to bed and wake up later.
Besides genetics, our chronotype is influenced by exposure to light, our eating schedule, our body temperature and other aspects of the circadian rhythm.
Are larks healthier?
A large study2 in 2018 reported that, after controlling for other factors, owls who described themselves as “definite” night people had a 10 percent greater risk of dying than “definite” morning people. Being a night owl was associated with twice the risk for psychological disorders, 30 percent more risk of having diabetes, 23 percent higher risk for respiratory disease, and 22 percent higher risk of gastrointestinal disease.
Lead researcher Dr. Kristen Knutson, however, was quick to clarify2 that the correlation doesn’t necessarily mean the owl chronotype is inherently less healthy or more dangerous. Instead, she said, it’s possible the trouble springs from the fact that the modern world—including work and school schedules—is really built for larks. An owl living in a lark world may have trouble getting to bed early enough to get a healthy amount of sleep when the alarm is set for 6 a.m. On top of that, it’s difficult to find healthy options late at night, like exercise classes or non-fast-food restaurants.
The mismatch between the hours some people’s bodies tell them to sleep and the hours society forces them to sleep lead to what’s been dubbed “social jet lag,”4 which is known to cause worse health outcomes.
How to adapt
If you’re an owl who’s able to get plenty of sleep on the schedule you prefer, embrace your natural rhythm: There’s probably no need to change a thing. But owls who need to get up early for school, work or another obligation may benefit from nudging their circadian rhythm closer to the schedule the world tends to run on.
A 2019 study5 of 22 owls tested some lifestyle changes to see whether people could adjust their own sleeping patterns, get more rest and avoid the ill health that comes from social jet lag.
For three weeks, the subjects were asked to:
- Wake two to three hours earlier than normal and get maximum exposure to outdoor light in the morning.
- Go to bed two to three hours earlier while minimizing light exposure in the evening.
- Maintain consistent bedtimes and wake-up times, even on the weekends.
- Eat breakfast immediately after waking up, lunch at the same time every day and dinner no later than 7 p.m.
Not only did these changes help people to shift their sleeping and waking times earlier, but researchers also noted physical and cognitive improvements.
In other words, even if you were truly born an owl, some simple lifestyle adjustments can help you feel better and get more done in this lark world.
Want to learn more about the science of sleep and how to sleep better? Here are 26 things you’ll probably be surprised to learn about the activity we all engage in each day.
- Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS,” Sleep, February 2017. https://academic.oup.com/sleep/article/40/2/zsw048/2662182
- Associations between chronotype, morbidity and mortality in the UK Biobank cohort,” Chronobiology International, March 2018. https://www.tandfonline.com/doi/full/10.1080/07420528.2018.1454458
- Bad news for night owls. Their risk of early death is 10% higher than for early risers, study finds,” by Amina Khan, Los Angeles Times, April 2018. https://www.latimes.com/science/sciencenow/la-sci-sn-night-owl-death-20180412-story.html
- Social jet lag is associated with worse mood, poorer health and heart disease,” American Academy of Sleep Medicine, June 2017. https://www.sciencedaily.com/releases/2017/06/170605085326.htm#:~:text=Results%20show%20that%20social%20jet,the%20likelihood%20of%20heart%20disease.
- Resetting the late timing of ‘night owls’ has a positive impact on mental health and performance,” Sleep Medicine, August 2019. https://www.sciencedirect.com/science/article/abs/pii/S1389945719301388