How to Create the Optimal Sleep Environment for You

 

Let’s face it, it’s pretty easy to take your bedroom for granted. Especially with everything going on right now, I bet a lot of people are falling into bed at the end of some very long days, worrying about life and the future, hoping that sleep will come quickly and last long enough to keep from feeling exhausted the next day.

Even in much easier times than these, it’s easy enough to lose sight of the importance of maintaining an optimal sleep environment. But it matters. A lot. Plenty of sleep problems arise directly out of our sleeping spaces, whether that’s from noise, or light, or temperature issues.

You’ve probably heard the advice to keep your bedroom like a cave: cool, dark, quiet. All good advice. But there’s more to it than that.

Since we’re all spending so much time at home right now, it seems like a good time to take a fresh look at our sleeping spaces, and put into action what the latest science reveals about what makes the most sleep-friendly bedroom.

What is the best bedroom temperature?

Without a doubt, this is the most common question I get from people about their sleeping spaces. The ideal temperature varies by individual, and a lot of this does depend on individual preference and tolerance for heat and humidity, as well as individual health factors, including body weight, hormone imbalances, the stages of menopause, and conditions such as obstructive sleep apnea and GERD. Here’s a thorough rundown of how the body manages temperature during sleep, and the many factors to consider in maintaining ideal temperature for your night’s sleep.

That said, there is a range that likely captures nearly everyone’s optimal temperature—and there’s some new research that shows that range, as well as potentially ideal single temperatures within it.

I find people often tend to think about air temperature as a stand-alone factor in our bedroom environments. But temperature interacts with other factors in critical ways that affect how we experience the heat or coolness of our sleeping spaces.

Scientists at San Jose State Research Foundation and NASA Ames Research foundation did a review of scientific research about what creates the optimal sleep environment. They found the ideal temperature range to be very broad—between 17-28 degrees Celsius, which is 62-82 degrees Fahrenheit.

But they also found that other temperature-related factors heavily influenced the optimal temperature within that range. One of those factors is humidity. I know we all complain a lot about the humidity in general—but I’m not sure people pay enough attention to humidity in their sleep environments. In their analysis, scientists found that the optimal range for sleep is 40-60% relative humidity. Depending on where you live, what time of year it is, that can mean you need to add or subtract humidity from your bedroom to sleep at your best.

Keeping your head cool doesn’t just feel comfortable for sleeping—it can actually help you slow down the racing thoughts that interfere with your sleep. Surprised? Research has shown that cooling the forehead slows down activity in the frontal cortex, and helps people fall asleep faster, sleep more deeply, and sleep longer. High levels of activity in the frontal cortex are common in people who can’t sleep. This is the area of the brain where ruminating thoughts take place. Cooling the forehead reduces the metabolic activity of the frontal cortex, and quiets the mind so you can sleep.

The Impact of Noise on Sleep

How loud does noise need to be to disturb your sleep? All of us are different, of course. And different sounds create different responses. Someone who can sleep through a thunderstorm will jolt awake at the sound of their child crying in the next room. The researchers at NASA and San Jose State, in their optimal bedroom environment analysis, found that threshold level for bedroom noise is 35dB. That means, to maintain an optimal sleep space, all noise needs to be at a decibel level below 35. What does 35 dB sound like? Here are some decibel level comparisons for perspective:

An airplane taking off is 150 dB

Thunder? About 120 dB

A lawn mower is around 100 dB

A bird call is roughly 40dB

Regular conversation between people sitting at a dinner table? 60 dB

A whisper? That’s about 20 dB

Your own breathing—and your partner’s, if they don’t snore, is about 10 dB. So, 35 dB is not quite 2x as loud as whispering, and definitely quieter than normal conversation. That’s pretty quiet, definitely a lot quieter than the TV volume that so many of us fall asleep to. We’re most likely to awaken from sound that’s 50 dB or less when we’re in the lighter stages of 1 and 2 sleep; deeper sleep awakenings typically require louder noises.

I’ve written before about the different types of noise that interfere with sleep, everything from snoring, to fireworks to TV and electronics to environmental noise. Each form of noise takes different remedies to address. All of them are worth addressing. White noise machines are a great sleep tool for masking unwanted noise, reducing awakenings, and increasing sleep amounts.

Total silence is not necessarily the solution, but an optimal bedroom is quiet. Melatonin has been shown to improve sleep quality against the effects of noise. In research, melatonin did a better job of protecting sleep quality in a noisy environment than earplugs. Earplugs can be useful, but people sometimes find them uncomfortable. And using ear plugs too frequently can lead to earwax buildup. When you do use earplugs, be sure they are clean (or new, if you’re using the disposable kind) with each and every use, to avoid exposing the ear canal to dirt and bacteria. If you suffer from tinnitus, I recommend avoiding using earplugs.

I love using earplugs for travel, but wouldn’t opt to use them at home every night. I’d rather see people use a white noise machine or sound machine to mask the noises you can’t control, and also address the underlying causes of noise-related sleep problems, whether that’s partners’ snoring, or a TV that runs late into the night without a shut-off timer.

For men and women, the ‘optimal’ sleep environment is different

A couple of these recent studies shed light on the differences in how men and women experience their sleep environments. A 2019 study looked specifically at gender differences in relation to temperature, and use of thermoelectric cooling technology. This study found women preferred a warmer sleep environment than men, requiring less powerful thermoelectric cooling to achieve optimal sleep in warm temperatures.

There are key differences in the ways men and women sleep. Men and women’s circadian clocks run differently. Men’s tend to run later and a little longer, which means women are apt to have a preference for waking earlier and going to bed earlier, across different chronotypes. Women, on average, spend more time in slow wave sleep, which may explain why science has shown that women tend to perform better when sleep deprived and to rebound more quickly from short-term sleep loss. Women and men also experience different, gender-specific sleep challenges at different points throughout adulthood, including the impact of menopause.

Don’t assume a one-size fits all approach is going to get both you and your partner the best sleep environment. You’ve got individual needs and preferences that may need individualized attention. Increasingly, sleep equipment is geared toward this level of individualization, whether for mattresses or the temperature of your sleep microclimate.

Pre-bedtime light will disrupt your sleep—but not all light works the same way to suppress sleep

The San Jose State/NASA study of optimal sleep environments confirms what I talk about a lot here: inappropriately timed light exposure in the evening hours before bed has a significant negative effect on your ability to

• fall asleep
• stay asleep
• get the optimal amount of time in each of the stages of sleep
• stick to a consistent sleep schedule, night after night

Poorly timed light exposure exerts a disruptive effect on sleep in several ways. Light is arousing. It stimulates the brain. That’s the opposite of what we want when we’re going to bed. And when your light exposure comes along with mentally stimulating content—say, from reading social media or the news online, or watching a fast-paced TV show—you’re getting a whole other layer of stimulation that takes your brain in the opposite direction from sleep.

Light at night also throws off circadian clocks—the body’s pacemaker, which regulates our daily sleep-wake cycles, and suppresses melatonin. These effects push sleep back to later in the night and they alter sleep-wake routines for nights to come.

But not all light has the same effect on sleep. Blue light—the short-wavelength light found in high concentrations in digital devices—is especially aggressive in disrupting sleep. For example, the researchers point to a study showing that use of e-readers before bed is linked to longer time to fall asleep, and less time in REM sleep compared to reading a paper book by lamplight. The blue light from e-readers was shown to suppress melatonin, shift circadian rhythms, and stimulate the brain, resulting in less sleep and more next-day fatigue, with less next-day alertness.

Limitations on light are essential to protecting sleep and creating an optimal sleep environment. Your bedroom should be dark for the duration of your sleep. No phones lighting up on the nightstand, no environmental light flooding in from outdoors. But your movement away from bright light—and especially blue light—needs to start before bed. That involves both limiting overall light exposure AND employing longer-wavelength light in your nighttime light sources. Red light, studies show, does not suppress melatonin and disrupt circadian timing as blue light does. You can easily install red light bulbs in your bedroom and in the areas of your house where you’re apt to hang out before bed.

Curating a restful sleep environment is one of the most rewarding and effective ways to protect and enhance your sleep. An investment of time and attention to your sleep space makes going to bed feel like a reward, and pays dividends in the form of deeper, sounder, more restful and restorative sleep.