People don’t hibernate during the winter the way bears and some other animals do. But we do tend to need more sleep in the winter months than in the summer, and that’s especially true in the northern hemisphere.
In fact, a survey by the American Academy of Sleep Medicine found that 34% of adults in the U.S. report sleeping more in the winter.
“From an evolutionary perspective, it made sense to sleep more and conserve more energy in the winter when resources are more scarce,” says Dr. Alex Dimitriu, who is double board-certified in psychiatry and sleep medicine and founder of Menlo Park Psychiatry & Sleep Medicine. “The opposite is true in the spring and summer—the days grow longer, food becomes more available and mating season begins.”
In a study in a 2025 issue of the journal Sleep, researchers analyzed data from 116,879 adults who used an under-mattress sleep sensor and found weekday variations and seasonal variations in their sleep duration. On the seasonal front, people slept an average of 15 to 20 minutes longer per night during the winter months in the northern hemisphere and 15 to 20 minutes less per night during summer in the southern hemisphere. The closer to the equator people lived, the less variation in seasonal sleep patterns they experienced.
Several environmental and behavioral factors are likely responsible for these seasonal differences in sleep, says study co-author Hannah Scott, Ph.D., a senior research fellow at the Flinders Health and Medical Research Institute: Sleep Health at Flinders University in Australia. “In winter, longer nights and reduced light exposure can promote earlier bedtimes and longer sleep durations,” Scott explains. By contrast, “summer months bring extended daylight hours, higher temperatures and more social activity, which can delay sleep onset and reduce sleep opportunity.” Indeed, longer hours of daylight mean delays in cues for sleeping.
But these aren’t the only seasonal variations in people’s sleep patterns. Research has found that human beings also experience changes in sleep architecture—the basic structural organization of sleep—throughout the seasons.
How Sleep Cycles Change by Season
A study in a 2023 issue of Frontiers in Neuroscience, involving 292 patients at a neuropsychiatric sleep clinic in Berlin, Germany, found some interesting seasonal differences: Rapid eye movement (REM) sleep was about 30 minutes longer during the winter than the spring and REM-sleep latency (the time it takes someone to enter REM sleep after falling asleep) was about 25 minutes shorter during the autumn than the spring. While slow-wave sleep (aka, deep sleep) was stable from the winter to the summer, it was 30 to 50 minutes shorter during the autumn months.
These variations are worth noting for a variety of reasons. For one thing, “slow wave sleep is associated with memory consolidation, body and brain restoration, and clean-up of numerous metabolic byproducts of a day’s worth of mental activity,” notes Dimitriu. “In REM sleep, [which] often includes dreaming, emotional regulation occurs, and people rehearse and simulate in dreams important themes in their lives.”
Besides affecting the quality of your sleep, these seasonal shifts have implications for how you might feel and function during the day. After all, “sleep plays a central role in supporting mental and physical health,” says Dr. Iman Hypolite, a board-certified psychiatrist who treats sleep issues related to depression and anxiety and is the owner of Aspira Health and Wellness, which is based in Atlanta. “Recognizing and addressing seasonal fluctuations is an often overlooked strategy for maintaining not only sleep but also mental and physical health and overall well-being.”
Why Sleep Variations Occur by Season
“The two biggest influences are ambient light and ambient temperature,” says Dr. Chris Winter, a neurologist/sleep specialist and host of the Sleep Unplugged podcast. “Depending on where you live, there may be more variations” in these factors and sleep patterns.
During the winter months in the northern hemisphere, shorter days with less daylight affect the body’s internal clock (our circadian rhythms). As the sun goes down, it signals the pineal gland in the brain to secrete melatonin, the hormone that regulates the body’s sleep cycle. “With earlier sunsets in the winter, the melatonin spike comes earlier, [which] can lead people to fall asleep earlier and stay asleep longer,” explains Dimitriu. “With less light in the morning, it also becomes easier to stay asleep.”
Meanwhile, environmental temperatures also play a role: “We are a lot more affected by ambient temperature than we think,” says Winter. “As body temperature declines and it’s cold outside, we tend to want to seek rest.”
For those with seasonal affective disorder (SAD), a mood disorder that typically occurs during the fall and winter months when daylight hours are shorter, the change can be especially pronounced. According to the National Institute of Mental Health, people who experience SAD produce too much melatonin, which can increase sleepiness and lead to excessive sleeping during fall and winter.
How To Handle Seasonal Changes in Sleep
The good news is: When it comes to sleep, you can do what comes naturally in a given season as long as you prioritize sleep hygiene. That means maintaining a regular sleep schedule, night after night, even on weekends and holidays. “While some variability is natural,” Scott says, “reducing large swings in sleep timing and duration, particularly across the week, can support better health and daytime functioning.”
“It’s okay to sleep more in winter, but it’s still important to stick with consistent bedtimes and wake times,” Winter says. In other words, keep regular bedtimes and wake-up times that allow for additional sleep during the season when you need it.
Good Habits for Better Sleep in Winter
Good sleep-promoting habits also include avoiding the use of electronic devices (including computers, TVs and phones), eating large meals, and doing anything exciting within an hour or two of bedtime, Dimitriu says.
When you wake up in the morning, expose yourself to bright, natural light if possible, even if it means sipping your morning coffee by a sunny window. Alternatively, you can use a light box or a dawn-simulating alarm clock, Winter suggests. And try to minimize evening light exposure, to keep your circadian rhythms steady and encourage melatonin release when you want it to occur.
If you’re not getting much natural light exposure during the day, you may benefit from taking a melatonin supplement in the evenings, Winter says.
Be sure to exercise regularly during the day because exercise increases deep sleep, Winter says. “Be aware of what your life and schedule look like during the summer when you’re active,” he adds. “Don’t let exercise slack off during the winter.” Even if you don’t exercise outside in natural light in the winter, it’s important to make physical activity a regular part of your days by exercising at home or at the gym.
In fact, a review of research found that sedentary behavior tends to be highest in winter (approximately 30 minutes less active time per day, compared to spring), and autumn tends to be the second least physically active season. The links between sedentary behavior and insomnia, as well as other sleep disturbances, are well documented. Fortunately, these can be reversed: A study in a 2023 issue of Scientific Reports found that each 60-minute unit of sedentary behavior that was replaced with moderate-to-vigorous physical activity led to better rest and sleep quality among women.
When it comes to all of these strategies, consistency is key. The goal “is to try to minimize the impact of seasonal changes on sleep,” Winter says. “Our brains love consistency,” which has repercussions for your sleep, mood, cognitive function and other brain-based processes.
