Ask Science: Is Cold Weather Good For Sleep?

Dark, quiet nights that start early, cool weather outside, hot tea and a warm blanket — sounds like a perfect recipe for good night’s sleep right?

The subject of getting good sleep has been a popular one recently, and one area of focus is on how external conditions like light, noise and even temperature may factor into our ability to get quality rest.

When it gets chilly outside, it’s definitely tempting to snuggle up under the covers and hibernate. Many of us may even notice changes in our habits related to the weather. But, does the chilly weather actually influence how we sleep?

We looked at the latest research and expert opinions to see what science has to say about temperature, weather and snoozing, and found some interesting points to share. Read on to see how cooler seasons can affect rest and how to get great sleep.

Temperature & Sleep: How Cold Weather Can Affect You

When considering things that may affect the quality of your sleep, temperature may not be on the top of your list but according to some researchers, it perhaps should be. Temperature plays an important role in the body’s functioning, and even during sleep how cool or warm you are at night can influence the quality of rest you receive.

How Cool Temperatures Affect Sleep

Sleep and wake cycles are governed in large part by our circadian rhythms. Around when we should be heading to bed, our body temperature takes a slight dip and stays lower until close to wake time. Body temperature also drops slightly in the early afternoon, coinciding with post-lunch sleepiness.

Science has yet to discover definitive causation between body temperature and sleep, but studies have shown connections. It appears that when temperatures are cool, this facilitates deep sleep. In contrast, warm temperatures may make sleep less restful.

In a Huffington Post article, professor Michael Decker, Ph.D., spokesman for the American Academy of Sleep Medicine, discusses temperature and rest. “As we sleep, our body acclimates to the room temperature,” he says. ” If we lower our body temperature a little bit in a cooler room, we tend to sleep better.”

Dr. Christopher Winter went into more detail in another article, saying that the sleep cycle is typically initiated when our core body temperatures drop, and that people with higher internal temperatures (like athletes) may have trouble sleeping when the room is not cool enough to allow this to occur. Studies he mentions find that ideal temperatures are between 60-67 degrees, with cooler temperatures in this range being linked to deeper sleep.

Experts on Web MD also say room temperatures that are too cold (or too hot) can affect sleep quality and make falling asleep more difficult. Though the doctors cited mention that individual comfort preferences vary, a range between 65 and 72 degrees is thought to be ideal for most.

A few studies have also looked at how temperature can affect sleep both in terms of biological impacts and on sleep quality.

Certain types of insomnia are believed to have connections to body temperature irregularities, meaning the evening temperature drop is delayed or the morning increase is advanced. Although conclusive evidence isn’t yet available, sleep hygiene experts typically recommend keeping temperatures cool as part of treating insomnia. If your core temperature is elevated due to a big meal or fever, sleep can also be difficult.

One side benefit: sleeping in a cooler room may help improve your health. One study published in the Diabetes journal found that cool temperatures (66F) stimulated brown fat growth compared to 75F and 80.6F. Brown fat is a good thing because unlike white fat, it helps your body burn energy and may help protect against obesity and diabetes.

Dog sleeping by fan
Photo from Flickr user Aris.Sanchez

However, cool temperatures can also have some risks, particularly when they are extreme or coincide with health conditions.

A 2012 review of data on temperature and sleep from the Journal of Physiological Anthropology found that heat and humidity affected slow-wave and REM sleep while cold did not. Cold temperatures were shown to affect cardiac activity, raising blood pressure and decreasing heart rate, which authors say may contribute to increased cardiac events in colder months and say the room temperature should always be above 10 degrees Celsius (50F).

Another study found that people with untreated sleep apnea experienced better sleep quality, slept longer, and were more alert in the morning at 60.8 degrees versus 75.2 degrees, but paradoxically experienced more symptoms at the lower temperature.

The best temperature for sleep varies for everyone depending on health and personal comfort preferences, but research shows and sleep hygiene experts agree that there is such a thing as too cold and too warm when it comes to nighttime temperatures.

Essentially, the prevailing wisdom is that somewhere in the 60s to low 70s is best, depending on what you personally find most comfortable. In the winter, that means a low thermostat at night not only cuts your heating costs, but may also help you sleep better.

Try a few different thermostat settings for a couple nights each to see where your Goldilocks’ zone resides. If your thermostat is programmable, try working with your body’s rhythms – set temperatures to gradually cool off around your bedtime, and raise slightly a little before your alarm goes off.

In the article referenced above, Dr. Winter also suggests trying products designed for optimizing sleep temperature to minimize cooling costs, such as performance sheets for breathability, gel pads for temporary cooling, and especially the ChiliPad for long-lasting mattress cooling or heating.

How Cold Winters Affect Sleep

While your indoor air and bedroom environment will likely play the biggest role, there a few ways that winter weather can affect sleep aside from changes it brings in indoor temperatures.

Less Sunlight

Winter days are shorter and the weather often keeps people bundled up or indoors. The dark nights can be good for turning in early, but they also dramatically reduce the amount of sunlight exposure for many people, which can affect circadian rhythms.

This can make you feel sleepy and sluggish all day, and throw off your bedtime at night leading to late nights and oversleeping or undersleeping. Experts suggest getting out in the sunlight first thing in the morning, and to limit bright lights and electronics at night.

For those who cannot get a daily dose of sun, bright light therapy has been shown to improve symptoms of seasonal affective disorder and other circadian rhythm disturbances.

Drier Air

Cold winter air typically contains less moisture and humidity than other seasons. Using electric heaters to warm the room temperature also contributes to indoor dryness, which can dry out mucous membranes and skin. When your nose dries out, this can force you to open your mouth at night to breath, leading to snoring and affecting how well you (and your partner) sleep.

If you run the heater often or live in a drier climate, a humidifier could prove helpful. The EPA suggests keeping indoor humidity levels around 25%-40% in the winter – if your sinuses are irritated, skin feels dry, or you notice lots of static, it could be low.  Cool mist humidifiers are generally suggested for congestion and children’s rooms, while ultrasonic models limit noise for sound-sensitive sleepers.

Colds & Flus

sick child
Photo from Flickr user Matteo Bagnoli

Winter season is also prime time for seasonal colds and flus which can affect sleep. Rather than breathing through your nose, which is considered ideal, congested sinuses force you open your mouth which can be uncomfortable and, as mentioned above, lead to snoring and disrupt normal sleep patterns. Fevers, body aches, coughs and other symptoms also make sleeping a struggle.

To get better sleep if you get sick, consider using a humidifier, keeping rooms dark, and sleeping with your upper body elevated to alleviate congestion. Staying hydrated and sipping on herbal tea before bed can also help. Web MD suggests being careful of stimulants and alcohol in cold medicines and recommends trying nasal decongestant sprays or strips for relief as an alternative.

Sleep Better During Winter

Based on research, studies, and expert opinions, here are a few tips for getting the best possible rest during cooler winter months:

  1. Keep ambient temperatures between 60-72 degrees.
  2. Use a humidifier if your nose or skin feels dry.
  3. Have a couple layers of blankets on your bed to accommodate changes in temperature or different preferences for couples.
  4. Keep hands and feet warm with socks or a warm water bottle.
  5. Use breathable bedding or climate-control accessories.
  6. Maintain a normal sleep-wake schedule even on the weekends.
  7. Get out in the sunlight at least 20 minutes per day, the earlier the better.
  8. Stay active during winter. Exercise supports better sleep habits.
  9. Take a warm bath 1-2 hours before bed – the drop in temperature as you get out of the tub can help your body prepare for sleep.
  10. Keep lights low after dark and try not use smartphones, TVs and close to your bed.
  11. Eat plenty of vitamin-rich vegetables and fruits and stay hydrated.

The human body is a highly-complex machine, and sleep is also a very complex process that is still not entirely understood by science. However, most researchers agree that seasons and temperature can affect rest quality and duration.

While cool room temperatures can be good for deep sleep, cold temperatures and dry air can also be disruptive.

Don’t set your thermostat too high or too low, pay attention to your bed and sleep environment, and try to maintain a regular schedule along with other healthy habits to get the best sleep during cold winter months.

How does the cold weather and the winter affect your sleep? Do you prefer sleeping when it’s cold or hot out?

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Rosie Osmun

Rosie is the Creative Content Manager and resident writer at Amerisleep. She finds the science of sleep fascinating and loves researching and writing about beds as an ambassador of the Amerisleep brand. Her favorite mattress is the ultra-plush Liberty Bed, and she is also passionate about traveling, painting, languages and history.