If you’re trying to sleep better, you’re probably paying attention to what happens at night: what time you go to bed, how much you’re on your phone, or how many times you wake up. But part of what determines how ready your body is for sleep starts much earlier in the day, first thing in the morning to be exact.

Not only that, it’s all about the sunlight you get when you first wake up.  That sunlight helps set the timing of your internal clock, which in turn affects how awake you feel during the day and helps determine when your body is ready for sleep later that night.

You Have A Clock Inside You

We all have an internal 24-hour clock, it’s called your circadian rhythm. It helps keep your sleep and wake times lined up with the day around you, and sunlight is one of the strongest signals it uses to do that. And the way to do that is to get outside within one hour of waking up.

When sunlight reaches your eyes in the morning, it gives your brain the information that the day has started. Later, as it gets darker, your hormone melatonin begins to rise to signal that it’s time for sleep. That whole process is happening during the day, which means your body starts preparing for tonight’s sleep way before you start getting ready for bed. (National Institute of General Medical Sciences)

Morning sunlight can also help you feel more awake during the day, and brighter sunlight can have a stronger effect on how awake you feel. Artificial light from lamps and overhead lights inside your home doesn’t give you the same outcome. You can have every light on in your home and still be getting a fraction of the brightness you’d get by stepping outside. (Systematic Review and Meta-Analysis of Light and Alertness)

This is where the connection to sleep becomes useful. Studies looking at the timing of light have found that brighter light earlier in the day is associated with better sleep, while brighter light later in the evening can interfere with it. Your body is paying attention to the pattern across the entire day. (Systematic Review of Light Exposure and Sleep)

How To Use Morning Sunlight

You don’t have to make this complicated. Getting outside within the first hour or so after you wake up is a good place to start.

Direct sun on your face isn’t required. You can walk, drink your coffee outside, take the dog out, sit outside for a while or work another part of your morning routine around being outdoors. Even in the shade, you’re still getting much more sunlight than you would from artificial lights inside.

Cloudy mornings count too. The sun hasn’t disappeared because there are clouds in front of it, and outdoor sunlight on an overcast morning is still much brighter than typical indoor lighting. On cloudy mornings, you’ll usually want to stay outside longer than you would on a bright summer morning.

There also isn’t one exact number of minutes that applies to everyone. The amount of sunlight you get changes with the weather, season, time of day and where you live. If you want a practical number to work with, 20 to 30 minutes outside in the morning is a reasonable place to start, with more time on darker mornings and less on very bright ones. Researchers looking at light and sleep have found that both the brightness of the light and the time you’re exposed to it affect the response. (PLOS Biology)

Sitting near a window can look bright to you, but it doesn’t give you the same amount of sunlight you get outdoors.

And if you’re awake before sunrise, turn on your regular lights and start your morning. Once the sun is up, get outside.

Where Coffee Fits

While coffee may wake you up, it does not do the same thing as sunlight will.

Caffeine makes you feel more awake by blocking adenosine, a chemical that builds while you’re awake and contributes to feeling tired. Morning sunlight affects the timing of your internal clock. Coffee can make you feel more alert for a while, while sunlight is helping keep your sleep-wake timing lined up with the day.

You may have heard that you should wait 90 minutes after getting up before having coffee. That rule has been repeated so often that it sounds settled, but there isn’t strong evidence that every adult needs to wait exactly 90 minutes.

If better sleep is the goal, the more useful caffeine question is how late you’re drinking it. A review of 24 studies found that caffeine reduced total sleep time, made it take longer to fall asleep and reduced deep sleep when it was consumed too close to bedtime. How late is too late varies with the amount of caffeine and how sensitive you are to it. (Sleep Medicine Reviews)

Your Evening Still Matters

The same system that responds to sunlight in the morning is still responding to light at night.

Bright light in the hours before bed can delay the rise in melatonin that normally happens in the evening. Research has found that even ordinary room lighting before bed can affect melatonin, so your cellphone isn’t the only light that deserves attention at night. (Journal of Clinical Endocrinology & Metabolism)

So if sleep has been difficult, look at the whole day instead of starting the conversation at bedtime. Get outside for sunlight in the morning, then lower the amount of artificial light around you as bedtime gets closer.

What This Means For Your Sleep

You can have a good mattress, a dark bedroom and a perfectly reasonable bedtime and still be overlooking something that happened 12 hours earlier.

Morning sunlight helps set the timing your body uses for the rest of the day. That timing affects when you’re awake, when melatonin begins to rise and when your body is ready to sleep.

So if you’re working on better sleep, your morning belongs in the conversation.

If you like understanding why everyday health habits work before trying to fit them into your life, that’s what we do inside Living Rewired. Each month we take one area of health, explain what’s happening and why it matters, and put the information into practice through a workshop, challenge, live coaching and a practical resource.

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