How Longer Days Affect American’s Sleep

By: SleepScore Labs  |  August 18th, 2021

We’re taking a look at how summertime’s longer days and warmer weather affect sleep for Americans nationwide. We’ll be examining whether seasonal differences matter for sleep and what longer summer days mean for our sleep-wake patterns. Plus, get science-backed tips to help keep your sleep in-check throughout the year. 

Do Changing Seasons Matter for Sleep? 

For millions of Americans, summer is synonymous with vacation plans, social gatherings, sunshine, and warmer days. However, while the extended sunlight may be nice, too much exposure to bright light close to bedtime may impair our production of melatonin, which is an important sleep-wake hormone, and further impact our sleep and circadian rhythms. 

“Melatonin is often referred to as the hormone of darkness because it’s stimulated and produced by the pineal gland in response to darkness,” says SleepScore Labs Applied Sleep Scientist Dr. Elie Gottlieb, Ph.D.  

In Seattle, sunlight may shine for up to 16 hours versus 14 hours in Miami.  

How Do Longer Days Shift American’s Sleep-Wake Patterns? 

Based on our analysis, sleep schedules do in fact shift during summer’s longer days. Throughout the month of June, Americans went to bed and woke up 10 minutes later than in the winter. For example, in January and February, the average bedtime was approximately 11:06PM, which shifted to 11:17PM by June and July. Wake up times also dipped in February to 6:56AM and peaked to 7:06AM in July. Changes in sleep-wake patterns during summer’s longer days weren’t limited to bedtime and wake up times. The longest days generally meant the shortest night’s sleep for Americans. 

Americans’ sleep duration decreased from 6 hours and 12 minutes in November to 5 hours and 59 minutes in June’s summer solstice, which points to just over a 10-minute decrease during the summer – that’s an extra one hour of sleep lost each week. 

These reductions were amplified during the weekends. During the summer weekends, Americans had nearly 20 minutes less sleep than on weekdays. Although the weekend should be a time to sleep-in and recoup from the work week, we found that the opposite was unfortunately happening. 

In addition to reductions in sleep quantity, we also found a slight decrease in the quality of sleep during the summer months. Sleep efficiency – a ratio of total sleep time to time in bed – fell from nearly 80% in November to just 78% during June’s summer solstice and 77% in sunny July. These numbers are below the 85% sleep efficiency threshold that the National Sleep Foundation has set to indicate a good sleep quality. 

We found a similar reduction for SleepScore – a 0-100 score based on 6 different sleep parameters measured within the SleepScore app. June and July clocked in with the lowest SleepScore’s at just over 79.  

Who Is Most Affected by Longer Summer Days? 

Our analysis also examined whether certain types of people were particularly impacted by longer summer days. At the time of the summer solstice, older adults over the age of 60 tracked almost 40 minutes less sleep at night than younger adults under 30. This shows older adults experienced greater reduction in sleep duration relative to the annual average. 

Gottlieb explains that the reduction isn’t surprising because sleep quantity and quality change dramatically throughout the lifespan. 

One thing is clear: Americans are having trouble meeting both the recommended quantity and quality of sleep per night during summer’s longer days. 

How Are Americans Sleeping Throughout the Year? 

American’s sleep schedules shift not only during the summertime, but also during the holidays at the end of the year.  

In December, we found a sharp rise and shift in sleep schedules. For example, bedtimes increased from approximately 11:07PM in November to 11:15PM in December. Wake-up times also increased from 7AM in November to 7:10AM in December.  

And luckily, the end-of-the-year shift in sleep schedules weren’t synonymous with less total sleep time. In fact, Americans slept most around this time of the year with an average total sleep time of nearly 6 hours and 15 minutes.  

And here’s some even better news for those dreaming about the end-of-year holidays: sleep quality also peaked in November and December, with American’s SleepScores surpassing any other month at 81 in November and remaining relatively constant to 80 through December. Sleep efficiency was also nearly 80% during the holiday seasons. ‘Tis the season to be sleepy!  

The holiday season truly is the most wonderful time of the year – especially for our sleep. 

Ideas To Keep Your Sleep In-Check No Matter the Time of Year 

Here are four science-backed tips to help you sleep better regardless what time of year it is. 

  1. Stay Out. Be sure to treat your bedroom as just that, a room with a bed where you sleep! Using your bedroom for working, eating, or watching TV is considered poor sleep hygiene, because doing those types of activities while in bed will train your brain to associate the bed as a place of wakefulness. If good sleep hygiene is your goal, the only things that should be happening in the bedroom are sleep and alone time with a partner. 
  2. Limit Screen Time. Sleep and light at night do not mix well. TVs, tablets, and computer monitors all emit blue light, which can interfere with our natural inclination to feel sleepy at night. Limiting screen time on your devices in the evening, using blue light filtering glasses after sundown, or adding a blue light filter screen protector will allow your body to release melatonin at the appropriate time. Instead of screen time, see if you can find other activities to help you wind down before bed, such as reading a book or taking a warm bath. 
  3. Cut the Stimulants. For many people, a major step in sleep improvement is identifying sources of caffeine and then reducing caffeine consumption, particularly later in the day. The stimulating effects of caffeine last for many hours, so it’s recommended to cut the caffeine after 2:00 in the afternoon. For the sake of your sleep, try switching to beverages that do not contain any caffeine during the afternoon hours and in the evening.   
  4. Watch What You Eat. Be mindful that your diet can affect sleep. Large meals or spicy foods can disrupt sleep. Finish your dinner on time and avoid late night snacking. If you have a large meal too close to bedtime, your body will focus on digesting as opposed to helping you get some sleep. 

SleepScore Labs Solutions 

Download the free SleepScore App for insights and articles on how well you sleep, the quality and quantity of your sleep cycles, and sleep improvement progress with science-backed tips and insights.  Download it for free from App Store and Google Play Store! 

You can also visit the SleepScore Store for a wide range of sleep-promoting products carefully curated by SleepScore Labs’ team of researchers including white noise machineslighting solutions, and more to support your sleep-wake schedule!  

Sleep well! 


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