The Surprising Effect Summer’s Long Days Have on Americans’ Sleep

Hot summer nights and extended daylight can make it tough to sleep. Here’s what you need to know.

Woman opening curtains and looking out to a bright day
baona/Getty Images

They say that in summertime, the living is easy. But is it also restful?

To learn more about the lazy days of summer and sleep, we teamed up with SleepScore Labs, our partner in sleep data and science, to analyze how Americans actually sleep when the days are longest, in June and July, as compared to other times of year.

Read on to explore some of the factors that could be causing your sleepless nights and learn a few helpful tips to stay well-rested in every season.

Summer’s long days can actually steal our sleep

After looking at 548,005 nights of year-round sleep data from 28,191 Americans, SleepScore Labs found that in summer, bedtimes tend to average 11 minutes later at night than at other times of the year. Though 11 minutes may not sound like a lot, when you average the bedtimes of more than 28,000 people over more than half a million nights, the change becomes much more significant. In January and February, the average bedtime was approximately 11:06 p.m., but by June and July, it shifted to 11:17 p.m. The reasons can be because of time off from work, gatherings with friends, blockbuster movies, and, of course, longer days with more evening light.

You may have heard the saying that “too much of anything isn’t good for anyone.” This is especially true for light.

Exposure to long summer solstice days has been known to impair the production of important sleep-wake hormones such as melatonin. These later sunsets — which can happen well past 9 p.m. in parts of the country (and past midnight in Alaska) may actually impact our sleep-wake cycle and circadian rhythms by delaying the melatonin secretion that informs our brains that it's time for rest.

“Light is the single largest factor on human circadian rhythms and is the major determinant of the timing of melatonin secretion by the pineal gland,” explains Nate Watson, SleepScore Labs' Sleep Advisory Board chair. “Melatonin is essentially ‘the darkness hormone,’ secreted around sundown to bring sleep.” So it stands to reason that when sundown is later, bedtime will be, too.

According to SleepScore Labs’ applied sleep scientist Elie Gottlieb, Ph.D., getting more light outdoors during the summer may trick our brains into thinking it’s still daytime. These light cues may shift our circadian rhythms back, pushing us to go to bed and wake up later during the summer months.

In the United States, sunlight hours during the summer solstice range from up to 16 hours in Seattle to nearly 14 hours in Miami.

And even though people tend to sleep in slightly later in summertime — July's average wakeup time is 7:06 a.m. — that later wake time does not make up the difference of summer’s later bedtimes.

How many hours of sleep do Americans lose during the summer?

According to SleepScore Labs’ data, the average sleep duration for Americans decreased by over 10 minutes during summer months — from an already alarmingly short 6 hours and 12 minutes in November 2019 (which is well below the recommended 7-9 hours recommended by the CDC) to only 5 hours and 59 minutes during the June 2019 summer solstice.

And while a 10-minute reduction in sleep may not sound like much, the cumulative effect over the long days of the summer season means missing out on over an hour of sleep per week.

“In summer, the delta between the sleep we need and the sleep we get widens,” says Watson. “Warmer temperatures’ impact on our ability to fall asleep along with increased social activities competing with sleep time are likely additional factors impacting these findings."

And unfortunately, Americans are not using those relaxed, warm summer weekends to catch up on sleep.

Instead, in measuring social jetlag during the summer, SleepScore Labs found that on Friday and Saturday nights in the summer, Americans averaged nearly 20 minutes less sleep than on weeknights during the summer.

Sleep quality also decreases during the summer

Sleep efficiency is the ratio of your time asleep to your total time in bed. So if you're tossing and turning or if you get into bed and read for a few hours struggling to wind down, you'll have a lower sleep efficiency ratio.

The National Sleep Foundation considers 85% sleep efficiency to be optimal. Though lower sleep efficiency may be a sign of restless sleep throughout the night, too-high efficiency may be a sign of exhaustion.

In line with the trends of worsened summer sleep, SleepScore Labs found that average sleep efficiency in the United States dipped from a high of around 80% in November down to a low of 77% in July, with the summer solstice giving people sleep efficiency of 78%.

Whose sleep is most impacted in the summer?

As people age, they become more affected by longer days.

During the summer solstice, the age group of Americans with the largest decline in average time asleep compared with annual nightly average was people over age 60.

Younger Americans, on the other hand, pushed their wakeup times latest into the morning during June’s summer solstice.

The result is that Americans over 60 got nearly 40 minutes less sleep each night during the June solstice in comparison to younger Americans (categorized as those under 30 years old).

“Sleep quantity and quality drastically change throughout our lives,” says Gottlieb, pointing out that this reduction isn’t entirely surprising. “Hallmarks of sleep changes in older adults include a reduction in total sleep, increased sleep fragmentation, and an earlier circadian timing.”

Other times of year when Americans’ sleep schedules shift

Summertime isn’t the only time of the year when US sleep schedules see significant changes.

Although bedtimes typically slide later as we move from the short, cold days of January to the midsummer months of June and July, Americans’ sleep schedules also shift during the winter holidays through New Year’s Eve.

In December 2019, SleepScore Labs found a noticeable 8-minute change in sleep schedules, from an average bedtime of approximately 11:07 p.m. in November to 11:15 p.m. in December.

Some good news: Unlike in summertime, the winter holidays’ later bedtimes do not correlate to less sleep time.

That’s because winter holiday wake-up times shifted 10 minutes later ⁠— from 7 a.m. in November to 7:10 a.m. in December, meaning that total sleep times actually improved. Americans get the most sleep of the year during December, averaging nearly 6 hours and 15 minutes.

Perhaps this is one of the greatest gifts of the holiday season. Especially if you, like the majority of Americans, are in need of sleep.

Tips to Keep Summer from Stealing Your Sleep

These five science-backed sleep hygiene tips can help get you on your way to a better night’s sleep during the summer and beyond.

  • Consistency is key. Consistency is your brain and body’s best friend and supports optimal sleep-wake patterns. That means sticking to a sleep schedule determined by time, rather than light, and doing your best to adhere to it every day – even on weekends.  
  • Think dark or dim before bed. Darkness will signal the production of melatonin, so pull down the shades, dim any bright lights, turn off those screens, and maybe even try a sleep mask.
  • Use daytime light to your advantage. While bright lights before bed can hinder sleep, morning daylight can actually help regulate the circadian rhythm. Step outside into natural sunlight in the morning for at least 15-30 minutes. But be mindful that excessive overnight light or light seeping through the blinds too close to your wake-up time can prematurely wake you up from slumber.  
  • Keep cool and chill out. Summertime means excessive heat and humidity. Both can keep you from falling — and staying — asleep. Adjust your thermostat to a more comfortable and cool temperature – most experts agree that the recommended bedroom temperature is between 60 to 68 degrees Fahrenheit.
  • Exercise (at the right time). Moderate exercise during the day is one of the best things you can do for your sleep at night.
Read More Summer Sleep Tips
Woman in bed with a white dog
No one wants to wake up drenched in sweat. Read on for tips and products to help you become a cool sleeper.
Exterior bright night shot of a building with a window view of a girl using her laptop
A nice dark space is critical for quality sleep. Here’s how to keep that brightness at bay. 
Two people sitting inside a tent enjoying a view of some mountains. The people are behind the view of the camera, with only their feet in the frame.
Research shows that spending time outside can help reset your sleep cycles. Here's why you should get outside, or five easy ways to mimic camping conditions at home.

If you found this article helpful, consider sharing it on TwitterFacebookPinterest, or Instagram or emailing it to any friends or family members who might benefit from a better night’s sleep. Sharing is caring!