Does morning light help you wake up?

Job 1: light sets your body clock

Your body runs on a rhythm of about 24 hours. It tells you when to feel sleepy and when to feel awake. Scientists call it your circadian rhythm. Most people just say body clock.

Light and dark have the biggest effect on that clock.¹² And the time of day you get the light changes what it does.²³

Here is some of the evidence.

• A lab study of 21 people mapped this out. Bright light in the morning moved the clock earlier. Bright light in the evening and early night moved it later.³
• In a camping study, a week with only natural light, and no electric light, moved people’s clocks earlier. Night owls moved the most.⁴
• A later study by the same group found that one weekend of camping did most of the job.⁵
• One study looked at more than 400,000 adults in the UK. Each extra hour a day spent in outdoor light was linked with three things: finding it easier to get up, feeling tired less often, and being more of a morning person.⁶ This kind of study cannot prove that light was the cause.

This is the strong part of the story. It is also the slow part. You feel the benefit over days, not minutes.

Job 2: light can make you feel more alert

Bright light can also perk you up on the spot. Here the evidence is weaker.

A review of 68 studies found that brighter light made people feel more alert in most studies, but not all. Far fewer studies tested reaction speed, and very few of those found an effect.⁷

Right after waking, the results are mixed too.

• Morning light after a night’s sleep

  No clear gain

  In a study of 11 people, bright blue-enriched light after waking did not reduce sleep inertia on most tests.⁸

• Light after being woken at night

  Early evidence

  In a study of 12 people woken from deep sleep, bright light led to fewer slips in attention. They also felt more alert and in a better mood.⁹

• One minute of light after a nap

  Early evidence

  In a study of 10 people, one minute of bright light after a short nap cut sleepiness. It did not improve test scores.¹⁰

So light after waking will likely help you feel more awake. Whether it makes you sharper is not settled.

What about wake-up lights?

Some alarm clocks slowly brighten the room before the alarm goes off. In small studies, people who used them said they felt more alert on waking.¹¹¹²

Test scores are less clear. One study of 16 people found no change.¹² One study of 8 people found slightly better scores.¹³

Outdoor light, indoor light and windows

Indoor light can feel bright. It is still a small fraction of daylight.²

In 2022, a group of experts advised people to get plenty of light in the daytime, and to use daylight first where they can. They noted that indoor light is usually at least ten times dimmer than outdoors.¹⁴

What about a window? We did not find a good study that compares a window seat with standing outside for waking up. What we can say is simple. A bright window gives you more light than a dim room. Outside gives you more than a window.

What you can try

• Get outside soon after you wake. Even a few minutes count.² Longer is better.
• Have your coffee or breakfast by the brightest window.
• Walk part of the way to work or school.
• Do it every day, weekends too.
• On dark winter mornings, turn on bright indoor lights when you get up. Then get outside once the sun is up.
• Keep evenings dim. Bright light late at night pushes your clock the other way.²¹⁴

Do you work nights or changing shifts? Then the timing rules are different. Our shift work guide covers that.

Are you a night owl who has to get up early? Morning light is the main tool for moving your clock earlier.² Our guide to building a steady wake-up routine shows how to use it.