For many, the ambient sound of the woods—birds chirping, streams gurgling, and leaves rustling in the trees—is one of the main draws of spending a weekend camping. The natural symphony of the forest floor is not just a delightful combination of sounds; it’s been scientifically linked to improved focus and relaxation. Often replicated on white noise machines, the low-decibel hum of nature can quieten the human mind better than artificial noise, further proving the link between calm, well-being, and the natural world.

That is, until the sun sets.

“There have been times when I’ve been on my own camping overnight and at that dusk time, when things start to get a little quiet, I’ve started to get a little nervous,” says Eric Larsen, a polar explorer, outdoor educator, and self-described “professional camper” who estimates he’s spent years of his life sleeping outside. Larsen has been charged by moose and had polar bears poke their noses into his tent at night. If mere nocturnal noise still makes him a little uneasy, there has to be a biological reason why sounds that are pleasant during the day can make your heart skip a beat at night.

According to psychologist Sésha Zinn, it’s more than just a fear of the unknown—it’s your brain actually working in a different way after dark. “Our vision takes up a lot of brain activity, so when it is inhibited, our brain can give more of its resources to our other senses,” says Zinn, whose research focuses on human behavior and trauma. This is the same reason people close their eyes to smell flowers, she says, as other senses can work better when not competing with vision.

Because our species is visually oriented—most of our sensory information comes through our eyes—not having use of our strongest sense in the dark causes our brains to release stress hormones. Zinn says those hormones encourage behavior intended to keep us safe, which includes interpreting innocuous sounds as possible threats. “Any sounds under these conditions will be interpreted as potentially dangerous,” says Zinn, “whereas in the daylight, we would not recognize many of these sounds as a concern.”

Because many predators hunt at night, humans evolved to be particularly vigilant in low-light environments.
Because many predators hunt at night, humans evolved to be particularly vigilant in low-light environments. Santa Monica Mountains National Recreation Area/Public Domain

There’s another reason humans are more scared of the unknown at night. It’s an evolutionary artifact from our deep past, when our ancestors were not that high up the food chain. Many predators are more active under the cloak of darkness, and potential prey must be wary.

“Practically, a lot of animals are more nocturnal, so just from a biological standpoint, fear can help you,” says Larsen. “It lets you know there’s a greater potential for danger.”

Our hypervigilant reaction to being in the woods at night is so ancient that even a professional camper like Larsen can’t escape it.

“Much of human behavior is deeply rooted in our DNA,” says Zinn. “No matter how long anyone spends in the outdoors, their startle response will always activate and be on high alert. It’s a matter of survival, our most basic human instinct.”

Humans also excel at distinguishing individual sounds, even if occurring simultaneously. With other senses, such as smell and taste, we perceive a combined stimulus: You smell a bowl of chili, not each ingredient. So even if the overall soundscape of the woods is pleasant, our brains are still going to isolate occasional distinct sounds that may not be. There’s no way to stop ourselves from focusing on the potentially threatening sounds, even if they’re only a small part of the forest symphony.

The heightened state of awareness we feel in the woods at night may be a biological default for our species, but there’s also a distinctly 21st-century wrinkle to feeling so unsettled. Humans today have quickly become attached to the dopamine hits that our phones deliver, says Zinn. We’ve also come to rely on easy access to technology for a sense of control and safety. And we spend most of the day—even when we’re out on the trails—occupied in some fashion. That changes when we settle in for the night.

“When you’re less engaged, you have a little more imagination accessible to you,” says Larsen. “When you’re lying in a tent at night, there’s not your footsteps, not your pack moving, no camp to set up, or task at hand. So you have time to focus on the other senses.”

The lack of access to technology in the nighttime forest can deliver a double dose of stress hormones. Not only does the loss of day vision trigger a primal survival state, but having no signal for your smartphone—that crutch for both security and distraction in modern life—can further amplify stress and anxiety.

“[Being] disconnected from our technology can feel like a loss of safety and control for our brains, even though we know experiencing nature with no distractions can be so wonderful for our mental and emotional well-being,” says Zinn.

To reduce unease you may feel camping in the wild, camp in a group and be an informed, responsible camper.
To reduce unease you may feel camping in the wild, camp in a group and be an informed, responsible camper. Bureau of Land Management Oregon and Washington, Public Domain

There’s no escaping our evolutionarily hardwired response to the woods at night—or, for most of us, our smartphone addiction. But there are ways to deal with it and enjoy the outdoors. Larsen, who runs programs to introduce new adventurers to multiday outdoor excursions, emphasizes two strategies to slow your brain’s roll: being an educated camper, and being with a group.

Start with learning about the area you’ll be, including what wildlife may be sharing the woods with you and how to be a responsible visitor. Minimum-impact camping is not only better for the environment, for example, but it also reduces the chance of attracting the four-legged locals. That’s particularly true in bear country, where you’ll need to take additional precautions, including with food storage and preparation. This kind of planning and knowledge can, says Larsen, manage risk and make you feel more in control. He adds that staying in a group can also help your brain relax a bit—not just because it’s safer than being solo, predator-wise, but because sharing the decision-making burden relieves the individual pressure to immediately interpret and react to every sound.

Ultimately, the best way to keep your brain from being on high alert all night may just be understanding the fear response, and accepting that it’s going to happen. And if you do find yourself jolted awake more often than you’d like, remember that it’s your brain working as it should, and something everyone experiences to some degree. “I’ve camped in so many woods where there’s like a flying squirrel crashing through the trees a little bit,” says Larsen, “but your brain thinks it’s some huge predator. Like a sabertooth tiger coming through.”