A Long Winter’s Nap: How Sleep Patterns Change Seasonally

As a child, you probably learned that animals like bears, squirrels and chipmunks hibernate for the winter. And while humans don’t hibernate, we do need more sleep during the winter. This is often referred to as our “winter hibernation”.

“We need between seven and nine hours of sleep each night, regardless of the season. But it’s common to see people sleeping more starting in late fall and through the winter, while needing less sleep during late spring and summer,” says Bernard Kaminetsky, MD, medical director, MDVIP.

As we move through the year, changes in weather patterns, temperature, work schedules, family responsibilities and social commitments affect our sleep needs. But the biggest factor in this issue seems to be the amount of daylight we get each day, which helps explain how the shorter days of winter trigger our need for more sleep. Here are three reasons how the amount of daylight affects your need for sleep.

Rapid Eye Movement or REM

German researchers conducted sleep studies on 188 participants. Those tested in the winter slept an hour longer and got 30 minutes more rapid eye movement (REM) than those tested in the summer, according to a study published in Frontiers in Neuroscience.

REM is the phase of deep sleep and the phase in which dreams occur. Ideally, REM should comprise 25 percent of your night’s sleep because it contributes to memory, concentration, mood regulation and immune function. Experts believe REM is affected by light and darkness. During winter months when we have less exposure to daylight, our body provides us with more REM sleep. This occurs process even if you live an urban area, surrounded by a lot of artificial indoor and outdoor light

“This is a small study, but it’s not the only one that found our bodies overcompensate for less daylight with more REM,” says Kaminetsky.

Circadian Rhythms

Circadian rhythms are 24-hour cycles that serve as the body’s internal clock. Circadian rhythms are controlled by a small portion of the brain known as the circadian pacemaker and it relies on daylight to help cue a broad range of physiological functions, including sleep. When natural light is sensed by our eyes, a group of retinal cells informs the brain, which uses the information to decipher the time of day and signal the body to when to perform processes based on that time.

This includes controlling the pineal gland’s production of melatonin – a hormone that helps your body unwind for the evening by lowering body temperature, decreasing alertness and promoting sleepiness. Melatonin is produced in response to darkness, which means levels are higher during winter months and lower during summer months.

“It’s important to maintain well-functioning circadian rhythms. Disrupted circadian rhythms can cause fatigue, jetlag and insomnia. Studies suggest it also can raise the risk for chronic conditions with ties to sleep deprivation such as heart disease, diabetes and some cancers,” says Kaminetsky. “Older adults and shift workers like firefighters and law enforcement officers are susceptible to circadian rhythm disorders.”

Seasonal Affective Disorder

Seasonal affective disorder (SAD) exacerbates the problem because the condition alters your levels of melatonin. There are two basic types – summer-pattern SAD and winter-pattern SAD. People with summer pattern SAD have lower melatonin levels, particularly on long, hot days. Summer-pattern SAD is notorious for causing poor sleep patterns and depression symptoms. Meanwhile, those with winter pattern SAD produce too much melatonin, causing sleepiness and oversleeping. Winter-pattern SAD is more common than summer-pattern SAD. Women tend to struggle with SAD more often than men as do people living in northern areas where winter is longer, and days are shorter.

“Talk to you doctor if you think you may have SAD,” says Kaminetsky. “They may prescribe medication for you or refer you to a specialist for treatment such as light therapy or counseling.”

4 Tips for More Natural Light During the Day

It’s important to get natural light first thing in the morning, as well as throughout your day. Yes, you will still probably sleep more during the winter and less during the summer, but properly regulated circadian rhythms helps you get the sleep you need and control SAD. Natural light is more effective than artificial light from table lamps and overhead lights, which is studies have linked to slowing the production of melatonin. Here are four tips that may help.

Spend more time outdoors during the day. There are many ways to spend more time outdoors. Start by walking, jogging or cycling outdoors. You can park further away in parking lots. Try socializing outdoors by going to the beach, fishing or visiting a park. Staying on top of chores such as raking leaves, washing your car or pressure washing your driveway can help.    

Sit by a window. Sitting near a window helps increase your daylight exposure. And since it’s important to get daylight exposure early in the morning, make it a habit to open the blinds/shades in your bedroom window after you’ve awakened.

Pay attention to light therapy. If you’re using light therapy to help manage headaches and emotional issues, know that red light therapy tends to increase melatonin production, while blue light therapy suppresses it.

Try technology that emulates sunlight. Sunlamps have been used for years to ease SAD and dementia. Sunrise alarm clocks also can help by gradually brightening bedrooms, helping you wake up along with the sunrise. Lastly, talk to you doctor about light glasses (also known as light goggles). They’re intended to alleviate jet lag but can help with daytime sleepiness and SAD.    

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