Spending time in nature is good for your physical and mental well-being in numerous ways. One benefit that doesn’t get as much attention as it deserves is how time outside can yield improvements in the quality and quantity of sleep. And you don’t have to go to a forest, field or mountain for these perks to kick in. Simply spending time outside during an ordinary day can make a difference.
“Being outdoors is a very under-rated intervention for improving sleep,” says Jade Wu, Ph.D., a behavioral sleep psychologist and clinical assistant professor of psychiatry at SUNY Upstate Medical University.
Daylight Benefits Sleep
Direct sunlight is one big reason for improved sleep. “As humans, we are daytime animals, and we do better when there are predictable patterns between days and nights. When we get lots of light exposure during the day and less at night, our circadian clocks are happy and things run well [in our bodies].”
Our circadian rhythms are our bodies’ internal 24-hour clocks that regulate cycles of alertness and sleepiness and influence when we’re likely to fall asleep and when we wake up. In addition, circadian rhythms affect our metabolism, body temperature, hormone release, mood and cognitive function, along with other essential body systems.
Exposure to natural outdoor light has a powerful effect on these elements. In fact, a study published in the Journal of Affective Disorders found that on average, the 502,000 adult U.K.-based participants averaged two-and-a-half daylight hours outdoors each day. For each additional hour spent outside during the day, the study correlated better mood and better sleep, including fewer insomnia symptoms, greater ease in getting up after sleeping, and less frequent tiredness.
The researchers attributed these effects to the better regulation of circadian rhythms, stemming from time spent outside. “A distinct light-dark rhythm, with dim light at night and bright light during the day, is essential for both the robust amplitude of circadian rhythms and its appropriate alignment with the waking day,” the researchers noted.
If you can’t swing two-and-a-half hours outside, take heart. “Based on what we know from circadian research, it’s best to spend at least 20 minutes per day outdoors,” says Wu. “The earlier part of the day is better for light exposure—you want full-on direct sunlight of 10,000 lux or more. If it’s a darker or cloudier day, you may need more than that.”
Exposure to the natural light-dark cycle of the day—without reliance on electrical lights indoors—can even shift your body’s circadian rhythms in a direction that’s conducive to better sleep. This is great news for people who enjoy camping: A study by researchers at the University of Colorado Boulder found that when healthy people went camping in nature for just one weekend during the summer, melatonin, a hormone that regulates the body’s circadian rhythms, was released 1.4 hours earlier and peak melatonin levels occurred an hour earlier during the night.
Outdoor Movement Helps Nighttime Sleep
If you’re not into camping or hiking, you can still reap the sleep-related perks of spending time outdoors because spending time outside can be beneficial for sleep for other reasons.
“Going outdoors usually means some sort of movement, which makes everything better,” Wu notes. As far as sleep is concerned, doing physical activity outside during the day can improve nighttime slumber “because we’re earning that recovery at night from using our bodies during the day,” Wu explains. In other words, expending physical energy during the day sets the stage for your body and mind to be ready to downshift into sleep mode at night.
Research has shown that people who exercised while exposed to natural light gained positive effects on their sleep patterns (including sleep onset latency, or how long it takes to fall asleep) and their overall sleep quality, compared to those who exercised in darker conditions. This may be partly because those who exercised in daylight had significantly higher melatonin levels at night compared to people in the other group.
Outdoor physical activity in the morning is ideal for many reasons, according to Satchin Panda, Ph.D., author of The Circadian Code. “A brisk walk, or any outdoor activity in the presence of bright daylight, is an excellent way to synchronize the brain clock.” Doing so will help increase alertness, enhance brain function and improve mood during the day; it will also improve sleep onset, sleep quality, and sleep duration at night.
The Stress Relief of Nature
Whether you’re moving or sitting on a park bench, being outside can also help reduce stress, which can have a positive effect on sleep. Research from Cornell University found that spending as little as 10 minutes sitting or walking in a natural setting improves people’s mental well-being and reduces their physiological measures of stress, such as heart rate and blood pressure. Not surprisingly, during the COVID-19 pandemic, surveys also found that people who spent more time outdoors reported longer sleep duration, along with better states of mind.
“Being in nature decreases the stress response, including the amount of cortisol flowing through our bodies,” Wu explains. “Cortisol should decrease in the early evening and get very low at night and increase in the morning.” When cortisol levels are fluctuating the way they should throughout a 24-hour period, people are more likely to have better quality sleep and fewer insomnia symptoms, she adds.
A related perk: Sleep fragmentation—in the form of brief micro-arousals that you may not even be aware of—“tends to improve when you have less chronic stress,” Wu adds.
Nature Is Calming
What’s more, the sensory experiences you get from spending time outside—including the sights, sounds and smells from what’s around you—can help relieve stress and improve nighttime shut-eye. After all, being in green spaces—such as gardens, parks or forests—or blue areas—such as near bodies of water—decreases the body’s chronic stress response, Wu explains. “When we’re in nature, we experience less stress and more calm.”
And if you’re tuned in to the fresh air, the sounds of birdsong or the rush of ocean waves while you’re outdoors, that’s even better for absorbing the perks of being in natural settings. After all, soaking up the visual and aromatic beauty of a lush garden or a forest setting or appreciating the grandeur of a mountain vista or the vastness of the ocean can instill feelings of awe or wonder. These positive emotions can instill a sense of being part of something larger than yourself. And “when we feel safe and connected [to the world], we’re more likely to sleep well,” Wu says.
The Outdoors Can Improve Our Sleep
Indeed, research has shown that exposure to green spaces—especially while walking or gardening—is associated with improvements in both sleep quality and quantity. And another body of research has found that people who spend more time outdoors throughout the week have a higher likelihood of having healthy sleep patterns.
However you choose to get your dose of outdoor time during the day, it’s likely to be good for your mood and functionality while you’re awake—and your nightlife while you’re sleeping.
