The chill of winter (at least, in most places) can make it oh-so-appealing to pass your free time hibernating indoors, maybe even wrapped in a blanket with a cup of tea. In that state, spending some extra time sleeping or taking a mid-afternoon snooze is just that much easier to do than in summer, when you’re more likely to be out and about. But it isn’t just greater proximity to the bed or couch that makes us crave more sleep in the winter. The season’s shifts in light and temperature also influence our circadian rhythm, leaving us physiologically more tired in the winter.

That’s right, feeling more tired and sleeping more in the winter isn’t just a product of feeling overall less motivated to go outside. It’s a real thing largely triggered by the change in photoperiod—aka the length of the day—that happens during the winter as the number of daylight hours shrinks, says sleep specialist Carleara Weiss, PhD, sleep advisor at Pluto Pillow. “Our circadian rhythm (aka biological clock) synchronizes with exposure to light,” she says. And with a whole lot less light naturally available to us in the winter, we can fall out of sync with our usual sleep-wake cycle, she says.

Why do we tend to feel more tired in the winter?

The decrease in daylight hours in the winter is the primary culprit, given the ways in which our circadian rhythm relies on light cues throughout the day.

In the morning, exposure to light “helps stop the floodgates of melatonin [a neurotransmitter that regulates sleep] and eases the transition from sleep to wakefulness,” says sleep specialist Rebecca Robbins, PhD, sleep expert at sleep-tech company Oura. But in the winter, as the sunrise arrives later in the morning, “we have less ample access to that light exposure, leaving us more likely to feel foggy and sluggish when we’re waking up,” she says.

“In the winter, we have less ample access to sunlight in the morning, leaving us more likely to feel foggy and sluggish.” —Rebecca Robbins, PhD, sleep expert at sleep-tech company Oura

Winter’s shortened days can also leave us feeling more tired in the evening. As the sunset arrives earlier, the drop in light cues our circadian rhythm to secrete melatonin and prepare for bedtime, says Dr. Robbins. This makes us feel drowsy long before we’re actually ready to sleep (since, who is able to just go to bed at 5 p.m.?) By the time our actual bedtime finally arrives, we might then struggle to fall asleep, as several hours have passed since twilight. “As a result, the brain may be less able to understand when we are supposed to be tired and when we are supposed to be awake in winter,” says Dr. Robbins.

The result is a double whammy: In the winter, it’s possible to both feel more tired when you want to be alert during the daytime and more alert when you want to be tired at night.

In some people, the surge in daytime tiredness is only compounded by a concurrent drop in mood, also prompted by the shortened photoperiod, says Dr. Weiss. “The decrease in daylight hours in the winter can be a trigger for seasonal affective disorder (aka SAD),” she says. “When dealing with SAD, people can experience depression, mood swings, social isolation, and lethargy, all of which can contribute to tiredness.”

At the same time, the drop in temperature in the winter can leave you naturally feeling sleepier—not just because you want to curl up in a blanket, but because cooler temps are more conducive for sleeping, says Dr. Robbins: “This may be part of our tendency to sleep longer in the winter compared to the summer, which, marked by hot temperatures, can lead to more disturbed sleep.”

5 tips from sleep doctors for mitigating wintertime tiredness

Just because it’s natural to feel more tired in the winter doesn’t make you powerless against sleepiness. By refreshing your sleep hygiene and taking steps to counteract the dimness of winter days, you can both optimize your nighttime sleep and feel more alert during the daytime hours when you want to be—even if the sun is nowhere to be found.

1. Get on a consistent sleep-wake schedule

The light-dark rhythm of our everyday life is already wonky in the winter, as we’re spending more time alert and doing things when it’s dim or dark out than we do in other seasons. Throwing off that rhythm even further by going to bed and waking up at random times will just cause your body to be even more confused about when it should be sleepy and when it should be wakeful—which is all to say, it’s extra important in the winter to stick to a sleep schedule.

That means going to bed at the same time and waking up at the same time every day, even on weekends, says Dr. Weiss. She also suggests bookending your sleep with consistent nighttime and morning routines to help signal to your body that, at night, it’s time to sleep, and in the morning, it’s time to wake up, she adds: “At night, leave time to unwind and avoid light from electronic devices for 30 minutes before bedtime, and in the morning, avoid snoozing, turn the lights on and expose yourself to bright light within 30 minutes of awakening, and eat breakfast to help your circadian rhythm reset.”

The idea is to make the time you spend right before bed and right after awakening as routine as possible, especially in the absence of clear cues from your surroundings during winter. “We call our circadian rhythm our ‘biological clock’ because it really does function like clockwork,” says Dr. Weiss. “The more consistent your routines around sleep, the more effectively you’ll establish a strong circadian rhythm and optimize your sleep quantity and quality.”

2. Make the most of whatever sunlight you can get during the day

Yes, sunlight in winter is limited—but during the hours that it is happening, it’s important to get exposure to it in order to remind your body that it’s daytime (and it shouldn’t still be pumping out the melatonin and making you sleepy). “Getting exposure to natural, daylight-spectrum light can help sync our circadian rhythm to the pattern of light and darkness in our environment [even in winter],” says Dr. Robbins.

3. Take an afternoon power nap

If you do it right, napping can be an incredible tool for nipping wintertime tiredness in the bud; it’s just essential that you don’t nap for too long or too close to bedtime. Otherwise, your body will just assume you’re going to sleep and enter into a deep sleep stage—from which it’ll be really hard to wake back up.

That’s why Dr. Robbins suggests opting for just a 20-minute power nap sometime before 3 p.m. This way, you’re sleeping for long enough to reap the benefits of a light sleep stage without the risk of falling into deeper sleep. In turn, you’re likely to wake up feeling re-energized—almost as if you had coffee, says Dr. Robbins, but without the potentially negative effect of caffeine on your ability to sleep later that night.

4. Embrace the cool temperatures at night

Sleeping well at night is key to avoiding tiredness the next day—and when it comes to getting good sleep, the cooler weather of winter is your friend.

If you live somewhere where it gets cold (or downright frigid) in the winter, you may be tempted to crank up the heat at night—but that would be a mistake, according to Dr. Robbins. Let your room stay as cool as the mid-60’s at night for optimal sleep, and if you live in a place without too much noise (and where it’s not below-freezing out), “consider sleeping with a window open in winter so you can enjoy the cooler temperatures and fresh air,” says Dr. Robbins.

5. Try bright light therapy

Certain kinds of artificial light can help fill the void created by the lack of natural light in the winter and boost your alertness during the day as a result. In particular, Dr. Weiss recommends bright light therapy, which is achieved by way of a light lamp or box (like the Northern Light Technologies Boxelite, $205) or bright light glasses like these ones from Luminette ($200). These types of products have been shown to help alleviate seasonal affective disorder when they offer full-spectrum visible light at 10,000 lux.

“The best advice is to use them in the morning right after waking up for at least 30 minutes and for no more than one hour,” says Dr. Weiss. This can help realign your circadian rhythm, as well as ramp up production of the feel-good neurotransmitter serotonin (much in the way that getting exposure to actual sunlight can, too).

In a similar realm, Dr. Weiss also suggests swapping out your regular alarm clock for a dawn simulator or sunrise alarm clock. (We love the Hatch Restore, $130.) This kind of alarm clock mimics the light of a rising sun, filling your room with increasingly bright light as your wakeup time arrives (even if it’s still pitch black outside). This can shuttle you into a lighter sleep stage before you need to wake up and ensure you get light exposure immediately upon waking—all of which can help you feel less groggy as you get out of bed, winter notwithstanding.