WHY YOU NEED SUNLIGHT AND DARKNESS TO GET THE BEST SLEEP

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It may sound odd, but it’s true: great sleep begins with your daytime habits, not just your nightly routine. Your body’s sleep system works on a precise chemical rhythm. Sunlight and darkness are two key cues that help keep it on track.

Four key chemicals—cortisol, adenosine, serotonin, and melatonin—work together to keep your sleep-wake cycle in sync. Let’s line them up and figure out how you can use light and darkness to get the best sleep possible.

1. CORTISOL

Cortisol is your body’s natural alarm clock. It is your body’s way of getting you up and ready for action. But if it stays too high at night, you’re going to be restless and have racing thoughts.

Want to keep cortisol in check? Start your day with sunlight. Morning light exposure helps regulate cortisol production, reinforcing your natural sleep-wake cycle. Morning sunlight boosts cortisol levels by 50%. This is beneficial early in the day. Higher cortisol improves immune function and alertness. It also helps set a timer to sleep about 14-16 hours later. On clear days, aim for 5-10 mins. On overcast days, try 20-30 mins.

Other ways to balance cortisol:

• NUTRITION: Balance blood sugar by eating whole foods and avoiding late-night sugar.

• EXERCISE: A regular sweat session can help manage stress—but avoid intense workouts right before bed.

• MEDITATION: Even 10 minutes of mindfulness can calm your cortisol-fuelled “to-do list brain.”

• SUPPLEMENTS: Some natural options like ashwagandha or magnesium may help to lower cortisol production.

It’s rather simple: less cortisol at night = better sleep. After cortisol does its job in the morning, that’s when adenosine steps in.

2. ADENOSINE

Think of adenosine as the little hourglass inside your body. The longer you stay awake, the more adenosine builds up. This creates “sleep pressure,” which makes you feel tired.

But it’s very important to know that caffeine blocks adenosine. That’s why your 3 PM latte is a double-edged sword—it keeps you alert, but it delays that sleep pressure building up. For optimal adenosine build up:

• DITCH CAFFEINE: Avoid it at least 10 hours before bedtime. Trust us, your future self will thank you.

• NAP WISELY: If you need to nap keep it under 20 minutes and avoid napping too late in the day.

• MOVE YOUR BODY: Exercise helps increase adenosine levels. This makes you feel sleepier at night.

The best way to work with adenosine? Go outside in the morning for sunlight. Stay active during the day. Let darkness tell you when to wind down.

3. SEROTONIN

Serotonin, known as the happy hormone, is the feel-good neurotransmitter. It helps stabilise your mood and regulates body temperature. Most importantly for sleep, it is the raw material for melatonin.

And guess what boosts serotonin production? Sunlight. Just 20 minutes of natural light exposure in the morning can make a huge difference.

Other ways to boost serotonin naturally:

• MASSAGE: Whether professional or DIY, massage helps to release serotonin.

• EXERCISE: Working out creates higher levels of serotonin. Even gentle activities like yoga, walking, or swimming can do wonders.

• NUTRITION: Eat more complex carbs. Enjoy fruits, veggies, and whole grains. They all help to boost serotonin production.

Higher serotonin = better mood and better sleep. Plus, fun fact: serotonin is also linked to delaying ejaculation.

4. MELATONIN

I’m sure you would have heard about melatonin supplements. It’s essentially your internal signal indicating that it is time to sleep. Produced in response to darkness, it regulates your sleep-wake cycle (a.k.a. your circadian rhythm). Here’s the issue: bright lights, screens, and indoor lighting fool your brain into believing it’s still daytime.

Want to give melatonin a helping hand?

• DIM THE LIGHTS: Reduce exposure to bright or blue light 30-60 mins before bed. Think warm lamps, or low-tech reading.

• GUT HEALTH: A healthy microbiome plays a surprising role in melatonin production. Eat fermented foods, fibre, and plenty of colourful veg.

• FOOD CHOICES: Some foods, like cherries, bananas, and oats, naturally support melatonin production.

We think it’s best to avoid melatonin supplements, except for helping to manage jetlag. They aren’t a long-term solution otherwise. They’re also unregulated in many markets, so dosages can vary widely between brands and what’s stated on the label.

To sum it up great sleep isn’t just about what you do before bed—it’s about your entire day.

• Get morning sunlight to regulate cortisol, serotonin, and adenosine.

• Stay active and eat well to support your body’s natural rhythms.

• Embrace darkness in the evening to trigger melatonin production.

These four chemicals help you get the deep, restorative sleep your body needs. Work with them, and you’ll sleep better than ever.