Many people sleep worse in winter. Here's what experts want you to know.

• Winter insomnia affects sleep quality during colder months.
• Causes include reduced daylight and stress from the holiday season.
• Bright light exposure and light therapy can help manage symptoms.

It's normal to feel sluggish during the winter. Cold temperatures and fewer hours of sunlight can mean less time outdoors and more time staring at our screens.

For some people, these cold-weather habits may contribute to a sleep disruption, known as winter insomnia. This isn't a clinical condition, but it might begin or worsen during the winter months.

"Although disturbances can vary, people commonly experience an increase in middle-of-the-night awakenings, waking up earlier than intended, difficulty falling asleep, or restless sleep," Dr. Nicole Moshfegh, PsyD, clinical psychologist and director of We Rise Psychology, Inc., told Business Insider. She explained that winter insomnia can be caused by a change in your mood or energy level, which affects your ability to unwind before bed or calm your mind when you wake up during the night.

Below, we talked to sleep experts about the signs of winter insomnia, what makes it worse, and what you can do if it's affecting your ability to get a good night's rest.

Are you experiencing winter insomnia?

Most adults need seven to nine hours of sleep for optimal health. But it's easy to overlook the quality of your sleep or how long it takes for you to fall asleep.

"People who experience winter insomnia have trouble falling and staying asleep, or getting restful sleep during the winter months," Dr. Raj Dasgupta, chief medical advisor for Sleepopolis, told Business Insider. "They usually notice more nighttime awakenings, lighter sleep, or a shift in their sleep timing."

He explained that winter insomnia is not a formal diagnosis. Instead, it's "a seasonal pattern of insomnia symptoms most likely from changes in light exposure, routine, and behavior during winter," he added.

Dr. Jade Wu, a board-certified sleep psychologist and Mattress Firm sleep advisor, agreed, saying there are no clinical signs to differentiate winter insomnia from other types of insomnia you might experience throughout the year.

"In some ways, it's easier to have insomnia in the summer due to the longer daylight late into the evening hours, which stimulates our circadian alerting signals," she said. These signals tell us when to wake up and be alert.

"But in winter, people are more likely to be sedentary and not have enough light exposure, so this can make them more vulnerable to insomnia and circadian problems," she said. Another factor contributing to poor sleep is our eating habits, such as reaching for certain foods out of comfort or convenience.

Causes of winter insomnia

"With reduced daylight, we have less outside signaling for our brains to know when it's day versus night, which can cause our circadian rhythms to become less strong or stable," Wu explained. "A less stable circadian rhythm can disrupt sleep quality."

Some people try to compensate for the lack of sunlight by relying on bright indoor lighting, which leads to greater alertness in the evening and difficulty falling asleep. "Over time, these shifts can disrupt the circadian rhythm and make sleep timing feel less predictable," Moshfegh said.

Less exposure to natural light, especially in the morning, may also contribute to seasonal mood changes, such as anxiety, depression, or seasonal affective disorder (SAD), Dasgupta noted. Signs of SAD include feeling depressed or being unable to find pleasure in previously enjoyable activities.

"Depression includes many physical symptoms like fatigue, sluggishness, and changes in appetite and sleep," Wu said. You may also notice mental symptoms, such as reduced motivation or difficulty concentrating.

"Because sleep and mood have a bidirectional relationship, the lower our mood, the more we experience sleep disturbances and vice versa," Moshfegh said. Both she and Dasgupta emphasized that the stress of the holiday season, combined with irregular schedules, increased alcohol use, and cold and flu season, can get in the way of healthy habits like exercising or cutting down on takeout orders.

"Many people experience increased loneliness, family challenges, grief, and pressure around goals and self-improvement during this time of year," Moshfegh said. "These experiences can all cause and contribute to stress, which is one of the most potent disruptors of sleep."

How to cope with winter insomnia

There are several ways to minimize sleep disruptions. "The most powerful tool we have is bright light exposure, which means being outdoors and being near brighter windows when you have to be indoors," Wu said.

If clouds are in the forecast or you work in low-light conditions, one option is to use a bright light therapy light box. "Make sure to check with your doctor before using a light box, because it can cause significant problems for some people," she said.