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

Hot summer nights can make it tough to sleep, and the longer days can make it even harder. Here’s what you need to know.

Woman opening curtains and looking out to a bright day
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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 take a look at how their users across America 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 possible reasons behind 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 stretch much later on average. 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. And due to the increase in daylight hours, all the light we enjoy during summer solstice (aka, the longest day of the year) may actually impact our sleep-wake cycle and circadian rhythms by signaling our brain to delay our much-needed melatonin secretion.

“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.”

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, that later wake time does not make up the difference of summer’s later bedtimes.

How Many Hours of Sleep Do Americans Lose in Summertime?


According to SleepScore Labs’ data, Americans’ average sleep duration decreased by over 10 minutes during summer months – from an already alarmingly short 6 hours and 12 minutes in November 2019 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, when you combine it, that deficit means missing out on over an hour of sleep each week during summer.

“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, SleepScore Labs found that on Friday and Saturday nights in the summer, Americans averaged nearly 20 minutes less sleep than on summertime weeknights.

Summer Sleep Quality Also Suffers


Sleep efficiency is the ratio of your time asleep to your total time in bed, tossing and turning, meaning the more time you spend in bed not sleeping, the lower your efficiency will be.

The National Sleep Foundation considers 85% sleep efficiency to be optimal, while lower sleep efficiency may be a sign of restless sleep throughout the night.

SleepScore Labs found that average sleep efficiency in the United States dipped from around 80% in November down to 78% around June’s summer solstice, hovering at 77% in July.

Whose Sleep Is Impacted Most in Summertime?


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

During the summer solstice, the age group with the largest decline in average time asleep compared with annual nightly average was Americans 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 a night during the June solstice when compared to younger Americans 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 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 eight-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.

Sleep quality also peaks in November and December, with sleep efficiency at nearly 80% during the holiday season.

Truly a wonderful time of the year. 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.

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