How Seasons Affect Your Sleep (And What to Do About It)

Key takeaways:

• Light and temperature shift your sleep patterns from season to season.

• People sleep about 30 minutes more in winter, with more REM sleep during darker months.

• The spring daylight saving time change is linked to short-term spikes in heart attacks, strokes, and traffic accidents.

• Small adjustments to light exposure, temperature, and routine can help stabilize your sleep year-round.

You probably sleep differently in January than you do in July, and most people do. Studies show that people sleep about 30 minutes longer in winter than in summer, and your REM sleep (the stage that supports memory and emotional health) increases by about 30 minutes in winter compared to spring [1].

That's because your sleep is tied to light and temperature, and both of those change throughout the year. Your body has an internal clock, called your circadian rhythm, that uses daylight to figure out when you should be awake and when you should be asleep. 

Here's how each season affects your sleep and what you can do to protect it.

How do seasonal changes affect your circadian rhythm?

Your brain produces melatonin, a hormone that makes you feel sleepy, when it gets dark. In winter, nights are longer, so your body has more time to produce melatonin. In summer, shorter nights mean a smaller window for melatonin production. Researchers have confirmed that both the amount and duration of melatonin your body releases change from season to season [2] [3].

But melatonin doesn't come from nowhere. Your body makes it from serotonin, a brain chemical that gets produced during the day, partly with the help of sunlight. When evening comes, your body converts that serotonin into melatonin. 

So if you're not getting enough sunlight during the day, especially in winter, you may not have enough serotonin to convert into melatonin at night. 

Temperature also plays a big role. Your core body temperature needs to drop by a couple of degrees before you can fall asleep. Experts recommend keeping your bedroom between 60°F and 67°F for the best results [4]. When summer heat or an overheated winter bedroom pushes your room above that range, falling asleep and staying asleep get harder.

Spring

Spring is the toughest season for sleep. Days get longer fast, which pushes your melatonin production later into the evening. You may notice that you feel wide awake at your normal bedtime, even though you still have to get up at the same time.

A year-long study tracking 216 people across the U.S. found that spring had the strongest effect on sleep. Participants woke up earlier and slept less than they did in winter, and the pattern lasted the entire season [5].

On top of those natural shifts, daylight saving time hits in March.

How does daylight saving time affect sleep?

Clocks move forward one hour at 2:00 AM on March 8. You lose an hour of sleep, and the effects last longer than you might expect.

Research shows that sleep disruption from the springtime change can last a week or more, not just one night [5]. One study found that people sleep about 40 minutes less on the Monday after springing forward [6]. This disruption is associated with a 24% increase in heart attacks on that Monday [7]. Additionally, the rate of fatal car accidents rises by 6% during the subsequent week [8], and stroke rates increase by 8% in the first two days after the time change [9].

The American Academy of Sleep Medicine (AASM) has called for eliminating daylight saving time and switching to permanent standard time. More than 20 medical and scientific organizations support this position [10].

What can help:

• Start going to bed 15 minutes earlier each night, beginning four days before March 8.

• Get outside for morning sunlight on Sunday. Sunlight is the strongest reset signal for your internal clock.

• Keep your wake-up time the same, even if you're tired. Sleeping in just drags out the adjustment.

• Cut off caffeine by noon in the days around the switch.

Summer

Summer produces the shortest sleep of the year. One survey found that people averaged 7.05 hours of sleep per night in summer vs. 7.41 hours in winter [11]. Wearable sleep tracker data shows a similar gap [12].

The main issue is the late sunlight during summer. In many northern U.S. states, the sun does not set until 8:30 or even 9:00 PM in late June. That extended light exposure keeps your brain receiving “daytime” signals long after your usual wind-down time. As a result, melatonin release is delayed, even though your wake-up time stays the same.

Heat makes things worse. Warm nights keep your core temperature from dropping the way it needs to in order to fall asleep. One study found that on unusually warm nights, rates of insufficient sleep went up, especially for older adults [13].

What can help:

• Blackout curtains or a sleep mask can make a real difference. They help block the late-evening light that delays your melatonin.

• Keep your bedroom between 60°F and 67°F. If you don't have air conditioning, a fan pointed at your body or a cooling mattress pad can help.

• Stick to a consistent wake time. Your circadian rhythm anchors more to when you wake up than when you fall asleep.

• Avoid big meals within two to three hours of bedtime. Digesting food raises your body temperature, which works against the drop you need to fall asleep.

Fall

Fall is often when people sleep best. Temperatures cool into the ideal range for sleep, and shorter days let melatonin production kick in earlier. If you can sleep with a window cracked open, the cool night air can actually improve sleep quality more than a thermostat set to the same temperature.

The fall clock change (November 1, 2026) is easier to handle than the spring one, since you gain an hour instead of losing one. Studies show that five days of earlier-than-usual wake times after the change still add up to a net loss of sleep over the week [14]. And the earlier sunsets can affect mood, especially if you're prone to seasonal affective disorder (SAD).

Fall allergens, like ragweed and dust mites from spending more time indoors, can also disrupt sleep by causing congestion and irritation at night.

What can help:

• Use the cooler weather to your advantage. If temperatures are in the 60s at night, try opening a window instead of relying on your thermostat.

• Get as much outdoor light as you can during the day, especially in the morning. As the days get shorter, maximizing your light exposure helps keep your circadian rhythm stable.

• If you deal with fall allergies, an air purifier in the bedroom and washing your bedding weekly in hot water can cut down on nighttime symptoms.

Winter

Your body tends to sleep the longest in winter, and the quality of that sleep changes, too. A 2023 study that measured sleep with polysomnography (a full overnight sleep study) found that REM sleep was about 30 minutes longer in winter compared to spring [1]. More REM sleep generally means better memory processing and emotional regulation.

But winter creates problems on the other side of the equation. You get less sunlight during the day, which lowers your vitamin D levels and your serotonin production. Since serotonin is what your body converts into melatonin at night, less serotonin during the day can actually reduce the quality of your sleep, even when you're sleeping more hours.

This is also the season when seasonal affective disorder (SAD) is most common. About 5% of U.S. adults experience SAD, and most of them report oversleeping rather than insomnia [15] [16]. SAD is closely tied to reduced sunlight, lower serotonin, and disrupted circadian rhythms.

Dry air from heating systems is another winter sleep disruptor. It can irritate your nasal passages and throat, causing congestion and discomfort that breaks up your sleep without fully waking you.

What can help:

• Morning light is the most important thing you can do for your sleep in winter. Even 15 to 20 minutes outside in the morning helps your body produce serotonin and keeps your circadian rhythm on track. If mornings are too dark where you live, a 10,000-lux light therapy box used for 20 to 30 minutes can do the same job.

• Run a humidifier in the bedroom. It helps with the dry air from your heater that can cause congestion and dry mouth at night.

• Don't give in to oversleeping. It might feel good in the moment, but consistently sleeping more than 9 hours can leave you feeling groggy and sluggish (this is called sleep inertia).

• Ask your doctor about checking your vitamin D levels. Deficiency is common in winter and has been linked to poorer sleep quality.

Support your wind-down routine naturally

If seasonal changes regularly make it harder to fall asleep or stay asleep, a gentle sleep aid can help while your body clock adjusts.

Sip2Sleep® is a plant-based, melatonin-free liquid sleep aid made with two clinically studied ingredients: Montmorency tart cherry extract, which contains natural precursors your body uses to produce its own melatonin, and Venetron®, a Rafuma leaf extract that supports serotonin levels and has a calming effect through the GABA system. Take 1 to 3 full droppers under your tongue about 30 minutes before bed, no pills, no water, and no next-morning grogginess.

If your sleep problems last more than a few weeks or start affecting how you function during the day, see a healthcare provider.

Frequently asked questions

Do people sleep more in winter? 

Most people do. Studies show about 30 extra minutes per night in winter compared to summer, along with more REM sleep. But longer sleep doesn't always mean better sleep. Reduced daylight can lower serotonin levels and leave you feeling groggy despite more hours in bed.

Why is it harder to sleep in summer? 

Late sunlight delays your melatonin release, and warm nighttime temperatures make it harder for your body to cool down enough to fall asleep. Both can cut into sleep quality even if you don't notice a change in how long you sleep.

Can seasonal changes trigger insomnia? 

Yes, especially during transitions. Shifting daylight patterns can push your internal clock out of sync with your schedule, making it harder to fall asleep or stay asleep. People who are already prone to insomnia tend to notice it most around the spring and fall time changes.

References

1. Seidler A, Weihrich KS, Bes F, de Zeeuw J, Kunz D. Seasonality of human sleep: Polysomnographic data of a neuropsychiatric sleep clinic. Front Neurosci. 2023 Feb 17;17:1105233. doi: 10.3389/fnins.2023.1105233. PMID: 36875666; PMCID: PMC9981644.

2.  Adamsson M, Laike T, Morita T. Annual variation in daily light exposure and circadian change of melatonin and cortisol concentrations at a northern latitude with large seasonal differences in photoperiod length. J Physiol Anthropol. 2016 Jul 19;36(1):6. doi: 10.1186/s40101-016-0103-9. PMID: 27435153; PMCID: PMC4952149. 

3. ANTTI KAUPPILA, AARRE KIVELÄ, ARTO PAKARINEN, OLLI VAKKURI, Inverse Seasonal Relationship Between Melatonin and Ovarian Activity in Humans in a Region With a Strong Seasonal Contrast in Luminosity, The Journal of Clinical Endocrinology & Metabolism, Volume 65, Issue 5, 1 November 1987, Pages 823–828, https://doi.org/10.1210/jcem-65-5-823

4. Smith K, as quoted in GoodRx Health, "What Is the Best Temperature for Sleep?" 2025. / Pacheco D, Sleep Foundation, "The Best Temperature for Sleep." 2024.

5. Mattingly, S.M., Grover, T., Martinez, G.J. et al. The effects of seasons and weather on sleep patterns measured through longitudinal multimodal sensing. npj Digit. Med. 4, 76 (2021). https://doi.org/10.1038/s41746-021-00435-2

6. Barnes, C. M., & Wagner, D. T. (2009). Changing to daylight saving time cuts into sleep and increases workplace injuries. Journal of Applied Psychology, 94(5), 1305–1317. https://doi.org/10.1037/a0015320.

7. Sandhu A, Seth M, Gurm HS. Daylight savings time and myocardial infarction. Open Heart. 2014;1:e000019. https://doi.org/10.1136/openhrt-2013-000019.

8. University of Colorado at Boulder. "'Spring forward' to daylight saving time brings surge in fatal car crashes." ScienceDaily. ScienceDaily, 30 January 2020. <www.sciencedaily.com/releases/2020/01/200130144410.htm>.

9. Sipilä JO, Ruuskanen JO, Rautava P, Kytö V. Changes in ischemic stroke occurrence following daylight saving time transitions. Sleep Med. 2016 Nov-Dec;27-28:20-24. doi: 10.1016/j.sleep.2016.10.009. Epub 2016 Nov 2. PMID: 27938913.

10. Rishi MA, Ahmed O, Barrantes Perez JH, et al. Daylight saving time: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2020;16(10):1781–1784.

11. Suzuki M, Taniguchi T, Furihata R, Yoshita K, Arai Y, Yoshiike N, Uchiyama M. Seasonal changes in sleep duration and sleep problems: A prospective study in Japanese community residents. PLoS One. 2019 Apr 18;14(4):e0215345. doi: 10.1371/journal.pone.0215345. PMID: 30998709; PMCID: PMC6472875.

12. SleepScore Labs. "How Seasons Affect Our Sleep: Sleep Patterns of Americans." 2023.

13. Jula, M. (2017, May 23). Climbing temperatures are keeping people awake at night. American Association for the Advancement of Science (AAAS). https://www.aaas.org/news/climbing-temperatures-are-keeping-people-awake-night

14. Harrison, Y. (2013). The impact of daylight saving time on sleep and related behaviours. Sleep Medicine Reviews, 17(4), 285–292. https://doi.org/10.1016/j.smrv.2012.10.001

15. American Psychiatric Association. (2024, March). Seasonal Affective Disorder (SAD). Psychiatry.org. https://www.psychiatry.org/patients-families/seasonal-affective-disorder

16. Wescott DL, Franzen PL, Hasler BP, Miller MA, Soehner AM, Smagula SF, Wallace ML, Hall MH, Roecklein KA. Elusive hypersomnolence in seasonal affective disorder: actigraphic and self-reported sleep in and out of depressive episodes. Psychol Med. 2023 Mar;53(4):1313-1322. doi: 10.1017/S003329172100283X. Epub 2021 Jul 29. PMID: 37010222; PMCID: PMC10071357.