Night owls and morning larks appear to be on complete opposite ends of the sleep spectrum.
But despite key differences in their sleep habits, new research has uncovered a common problem among both types of folks: poor sleep quality. SleepScore Labs, our partner in sleep data and science expertise, analyzed sleep data on nearly 26,000 individuals and found that people with more moderate chronotypes tended to have the highest quality sleep.
“Contrary to our expectations that sleep-wake patterns would be preserved in morning types as a sign of better health, both extreme evening and extreme morning types showed signs of poor sleep,” says Elie Gottlieb, Ph.D., applied sleep scientist at SleepScore Labs.
Here’s how sleep quality takes a nosedive among serious night owls and dedicated morning larks — along with the one factor that makes a difference in everyone’s ability to get a good night’s rest.
How sleep quality varies among chronotypes
Night owls and morning larks have significantly different sleep habits, but does their sleep quality vary as well? To probe for answers, SleepScore Labs gathered data on more than 1.4 million nights logged by 25,933 people. The participants, 59% of whom were female, ranged in age from 17 to 100 years old.
The researchers found a strong difference in total sleep time (an important factor in sleep quality) among people with different chronotypes. Strong night owls and strong morning larks both slept an average of 5 hours and 44 minutes per night, whereas those who fell in between slept anywhere from 5 hours and 55 minutes to just over 6 hours per night.
These strong chronotypes also had their own individual signs of poor-quality sleep, as well. Sleep efficiency, or the percentage of time spent actually sleeping while you’re in bed, tended to be the worst among those strongest morning types. They typically slept about 77% of the time they were in bed. Sleep efficiency improved as people skewed more toward strong evening types, who maxed out at nearly 80% sleep efficiency.
On the other hand, early birds fared much better when it came to sleep onset latency (the amount of time it takes you to fall asleep after hitting the hay). They had about 17 minutes of sleep onset latency, whereas night owls took an extra minute or two, on average.
The chronotypes also varied in another key measurement of sleep quality called WASO, wakefulness after sleep onset. WASO measures how much time a person spends awake due to interrupted sleep after falling asleep, such waking up to use the bathroom or awakening due to thermal discomfort. Strong night owls had the lowest WASO scores of the bunch at roughly 22%, an indication that they had higher-quality sleep. The WASO percentages climbed gradually from slight evening types to strong morning types, who had the highest WASO score at just over 26%.
Understanding poor quality sleep among strong chronotypes
Given the mixed data, the verdict’s still out on whether night owls or morning larks have the worst quality sleep. But overall, the findings showed that those at the extreme ends of the spectrum tended to have poorer quality sleep than those who fell somewhere in the middle.
This may be explained, at least in part, by the lower levels of light exposure people who go to bed very early or wake up very late tend to have, says Dr. Stephanie M. Stahl, a sleep medicine physician and assistant professor of clinical medicine at Indiana University School of Medicine.
“It probably has to do with maintaining a circadian rhythm within normal sun and dark time — those are such strong factors in promoting melatonin production,” she explains. “It’s best to try to sleep when it’s dark and be awake when it’s bright outside. If we fall outside of that, it tends to affect sleep quality in terms of how melatonin is produced.”
Another factor that may impact sleep quality among extreme night and morning types is the fact that the workplace and society at large are built for middle-ground chronotypes. That forces people to adjust their bedtimes and wake-up times in ways that might go against their natural tendencies.
“People have to work against their chronotype to fit into the societal expectations that they have a fairly neutral chronotype. That conflict of daily life can impair sleep quality,” says Jay Olson, Ph.D., postdoctoral scholar at McGill University’s department of psychology, who has studied sleep quality and jet lag.
Age affects everyone’s sleep quality
No matter the chronotypes, one universal factor impacted people’s sleep quality: age.
In every metric analyzed by SleepScore Labs, age seemed to be associated with worse sleep outcomes. Older participants tended to have lower total sleep time and reduced sleep efficiency. Sleep onset latency declined and WASO percentage increased with age. Put together, these measurements suggest that achieving high-quality sleep gets more challenging as the years go on — for night owls, morning larks, and the birds in between.
“We found that age-related changes to sleep were not driven by chronotype, suggesting that issues with maintaining and initiating sleep as we age likely stem from internal, physiological changes to our brain’s sleep and circadian centers — not our preferred bed and wake times,” explains Gottlieb.
Scientists have known for a while that sleep quality changes as we age. This can include decreases in sleep time, difficulty falling asleep, less time in deep sleep, and waking up more frequently. So the latest finding isn’t necessarily groundbreaking, but it helps to put our chronotype (and the associated challenges that it comes with) into perspective when thinking about our sleep health.
How to assess your sleep quality
An occasional bad night of sleep isn’t a big deal (aside from the intense grogginess you may feel the day after). But chronic sleep problems have been associated with all sorts of serious health problems, like increased risk of dementia, heart disease, cancers, and type 2 diabetes, so it’s worth taking a close look at your sleep habits and exploring ways to improve them.
Apps, smart watches, and fitness trackers can all give you important data on how well you’re sleeping. You don’t have to go high-tech to assess your sleep quality, though.
“In research, we use an extremely simple sleep quality scale,” says Olson. “We ask, ‘From one to 10, what was the quality of your sleep last night?’ Generally, if you’re scoring around a seven or higher, that’s pretty good.”
How to improve your sleep quality
If your scores tend to be consistently low, there are some tweaks you can make that could boost your sleep quality.
Get into the light
“You can support your circadian rhythm by harnessing the power of light,” says Gottlieb. “Ensure you get at least 15 minutes of bright sunlight within the first hour of waking up in the morning and use the sunset as a reference for when you should start to dim any bright lights at home.”
Keep a consistent schedule
You can also adopt sleep hygiene practices, like going to sleep and waking up at the same times every day, banning electronic devices from your bedroom, making sure your sleep environment is dark and cozy, exercising during the day, and being careful about consuming alcohol or caffeine close to bedtime.
“Sleep hygiene is something that can improve sleep quality for both morning birds and night owls,” says Olson.
With the right habits in place, you can increase the chances of getting good quality sleep throughout your life, no matter your chronotype or how many candles are on this year’s birthday cake.