The lightbulb is great. Thanks, Thomas Edison. But it’s ruining our sleep.

Instead of our lives revolving around the rising and setting of the sun, we have artificial light, so we can start our days earlier and end our days even later. And now our circadian rhythms are all messed up.

Modern humans should naturally be falling asleep between 8 pm and 10 pm every night. Instead, our internal clocks have been pushed back an average of 2 to 3 hours. That means you’re missing out on 2 to 3 hours of precious sleep every night.

I know—it seems unreasonable to start and end your day with the sun. But our circadian rhythms are highly dependent on light exposure, so you need to work sun exposure into your daily routine. Here’s why:

How Sunlight Affects Your Sleep

First, let’s talk about circadian rhythms. According to the National Institute of General Medical Sciences, “Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. These natural processes respond primarily to light and dark and affect most living things.”

While our circadian rhythms can affect hormone release, eating habits and digestion, and body temperature, we usually associate circadian rhythm to sleep patterns. And it all starts in the hypothalamus.

Hold on—it’s about to get technical.

The suprachiasmatic nucleus, or SCN, is in a part of the brain called the hypothalamus. It receives direct input from the eyes. And the SCN controls the production of melatonin—the hormone that makes you sleepy.

Here’s how it works: The SCN receives information about incoming light from the optic nerves, which send information from the eyes to the brain. When there’s less light (like at night), the SCN tells the brain to make more melatonin, so you get sleepy.

This is a great system. However, it doesn’t work as well when artificial light continues to send signals to your optic nerves, preventing your brain from producing melatonin at the right time.

How to Get the Right Sun Exposure

Sun exposure can be tricky. On one end of the spectrum, sun exposure helps create vitamin D in the skin and prevents depression. On the other end of the spectrum, too much sun exposure can cause skin cancer. So, you want to find that sweet spot right in the middle where you’re getting the right amount of light to your optic nerve without roasting yourself.

Bright Evening Light 2 Hours Before Bed

To help you fall asleep, keep the lights dim for 2 hours before you go to sleep. Exposure to bright evening light 2 hours before bedtime shifts your sleep time back, so you’ll get sleepy and fall asleep later.

If you don’t have dimmers on your lights or can’t avoid the sunlight 2 hours before bed, consider wearing sunglasses (the cool wraparound ones work best).

If you find yourself getting sleepy too early in the evening, go into a well-lit area to make yourself more alert.

Morning Sunlight

Getting morning sunlight can help you sleep better at night. Bright morning light can shift your bedtime earlier. So, if you want to start going to sleep earlier in the evening and waking up earlier in the day, try taking in the bright morning sunlight. For example, try eating your breakfast outside or next to a sunny window.

On the other hand, if you’re waking up too early, keep the lights dim until the time you want to wake up.

Light Throughout the Day

Get outside in natural sunlight for at least 30 minutes every day. Make if part of your daily routine—read the paper on the patio, break up your day with a mid-day walk, etc.

But what if it’s cloudy and overcast? Even when sunlight is filtered through clouds or rain, it continues to have the same effect.

While leisurely strolls through the park aren’t always an option for everyone, every day, all year round, it’s important to try to work light therapy into your routine. The most important thing is to make sure the light hits your eyes directly, so your optic nerves can send your brain the right signals.

Light Boxes

Light boxes sound like a great idea to replace actual sunlight, but it doesn’t quite do the trick. Many light boxes provide a light intensity of about 10,000 lux or less, while the sun’s intensity is 100,000 lux. So, you’re only getting about a tenth of the light the sun offers.

Light boxes are also really expensive. You can either spend several hundred dollars on a light box, or you can go in the sun for free.

Now that a lot of us work from home and have everything delivered to our front door, there’s a good chance we may never see the sun again. But that would be bad. It turns out that artificial light, while it can mess with our brain signals, doesn’t replace the benefits of actual sunlight. So, get out from behind that desk and take in some rays. You’re sure to see some improvement in your sleep and mood.

Want a better night’s sleep? Check out our “12 Tips for Better Sleep” blog series:

Part 1—Keep a Regular Sleep Schedule

Part 2­—Exercise at the Right Time

Part 3—Avoid Caffeine and Nicotine

Part 4—Avoid Drinking Alcohol

Part 5—Avoid Big Meals and Drinks Before Bed

Part 6—Avoid Medicines that Ruin Your Sleep

Part 7—Don’t Take Late Nap

Part 8—Relax Before Bed