The #1 Thing You Can Do to Feel Less Tired in the Morning—and It’s So Simple

For some people, waking up in the morning is easy. They don’t even need an alarm clock to start every day feeling refreshed. And then there’s the rest of us, who hit “snooze” way too many times and feel groggy no matter what time we went to bed. Fortunately for us, a new study out of Japan has found something that helps: exposure to natural light in the morning. Though this relationship has been studied before in a medical context, this research takes an architectural approach, determining how this knowledge can be applied outside of a lab. Here’s what the study found, and how you can take advantage of the natural light in your own home.

How to Use Natural Light to Decrease Morning Fatigue

The study, published in the journal Building and Environment, tested three different morning scenarios: exposure to natural light from dawn until waking up, exposure to natural light 20 minutes before waking up, and no exposure to natural light before waking up. The researchers found that the group that wasn’t exposed to natural light before waking up dealt with the most morning fatigue. Of the other two groups, the one that got 20 minutes of exposure to natural light was the least fatigued after waking up. 

So when it comes to natural light in the morning, why isn’t more exposure better? It comes down to the fact that dawn time for natural light varies depending on the season and region, says Daisuke Matsushita, PhD, lead author of the study. The weather and the direction of the windows also affect the time that a room fills with natural light. “Sunrise time in Japan varies from about 5 a.m. in summer to 7 a.m. in winter,” Matsushita explains. “Today’s life is tied to a fixed time for commuting to and from work, regardless of sunrise time. Morning light can lead to light sleep, but 5 a.m. is too early. It seems about 20 minutes before waking up is preferable.” This is in part because light during sleep has been shown to cause worsened sleep, he explains. 

Why Does Natural Light Help Us Wake Up?

So why, exactly, does natural light have such a profound effect on the way we sleep and wake up? It comes down to our circadian rhythm—or the body’s internal clock that tells our organs what time it is outside, says Dr. David Benavides, MD, sleep medicine physician.

“If light exposure is mistimed, the [circadian] clock becomes disrupted,” says Maj. Allison Brager, PhD, neuroscientist. “Natural light provides the strongest and most robust signal to the circadian clock, allowing for optimal rhythms of hormones, mood, and behavior.”

Although a lot of our circadian rhythm is genetically pre-programmed, Benavides says, we can influence aspects of it—and light is its strongest external cue. “As light enters our eyes, it helps regulate the body’s master clock, also known as the ‘suprachiasmatic nucleus’—located in the brain,” he explains. “This in turn signals whether to shift the time/rhythm earlier or later. Mastering this concept can improve sleep-wake timing, mood, energy, and overall health.”

But why is having a regulated circadian rhythm so important? “Circadian health is grounded in extensive research and clinical guidance, and a solid tenant in a sleep physician’s training for good reason,” Benavides says. “Optimizing circadian health can benefit not only those with sleep problems, but also healthy individuals as well.” For instance, in April 2025, the American Heart Association released a scientific statement emphasizing that healthy sleep includes not only duration, but also timing, regularity, and circadian alignment—with disruptions independently increasing the risk of hypertension, diabetes, obesity, and heart disease.

What About Artificial Light?

According to the findings of the study, 20 minutes of exposure to natural light before waking up is ideal for reducing morning fatigue. But getting the perfect amount of natural light is easier said than done—unless you have your curtains on a timer, or live with someone willing to open your curtains for you at a particular time each day. 

This is where sunrise alarm clocks come in. Instead of waking you up with a jarring sound, these alarm clocks gradually fill your room with light—mimicking dawn—becoming bright just before you wake up. Most also are programmable, allowing you to set it so you get 20 minutes of light before you actually have to get out of bed. But are sunrise alarm clocks as effective as natural light?

According to Matsushita, while they do have a similar effect, natural light is preferable. “We have long adapted to the cyclical transitions of natural light,” he explains. “Even if we simply match the illuminance and color temperature, there are differences in spectral distribution and frequency, at least between natural and artificial light, and these differences can affect the quality of your sleep.”

Brager and Benavides agree that natural light is the better option, but sunrise alarm clocks can be an effective substitute—especially in the darker winter months. But it’s still a good idea to get some natural light as soon as you can in the morning. “I generally recommend patients step outside within 30 to 60 minutes or waking for at least 15 minutes to get natural sunlight, when possible,” Benavides says.