It's counterintuitive, but excellent sleep needs light and darkness. Your body's sleep system follows a detailed chemical schedule. Sunlight and darkness are what keeps it on track.

Your body produces four key chemicals: cortisol, adenosine, serotonin, and melatonin. They 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 gets your body up and prepared for action. But if it stays too high at night, you’re going to be restless and have racing thoughts.

Ways to balance cortisol:

Start with light in the morning. This light regulates your cortisol production and helps put you on schedule for the rest of the day and sleep cycle. Morning sunlight stimulates cortisol levels by 50%. That level is key in the morning.

Higher cortisol improves immune function and alertness. It sets a timer to sleep about 14-16 hours later. On clear days, aim for 5-10 mins of morning sunlight. On overcast days, you may need 20-30 mins.

Other ways to balance cortisol:

• NUTRITION: Balance blood sugar by eating whole foods in your evening meal and avoiding late-night sugar.
• EXERCISE: A regular sweat session can help manage stress. 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.

Less cortisol at night means better sleep. After cortisol does its job in the morning, that’s when adenosine steps in.

 

2. ADENOSINE

 

Adenosine works like a pressure cooker within your body. The longer that you're awake, the more adenosine builds up. This leads to greater pressure on the body to go to sleep.

But it’s important to know that caffeine blocks adenosine. Adenosine and caffeine are chemically similar. So much so, that caffeine attaches itself to adenosine receptors in the brain, blocking adenosine from doing it's job. That’s why your 3 PM coffee break is a double-edged sword. It keeps you alert in the afternoon, but it delays that sleep pressure building up. For optimal adenosine build-up:

• CAFFEINE: Avoid it at least 10 hours before bedtime.
• 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. 
• GET OUTSIDE: Get morning sunshine as soon as you can.

 

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. Foods rich in tryptophan like eggs, salmon, turkey, tofu, seeds, nuts, oats, and bananas. Keep your gut healthy with fermented foods like yoghurt, kefir, or kimchi.

Plus, fun fact: serotonin also plays a part in men being able to keep things going longer in bed. Higher serotonin = better mood, better sleep and better sex.

 

4. MELATONIN

 

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

How do you give melatonin a helping hand?

• DIM THE LIGHTS: Reduce exposure to bright or blue light 30-60 mins before bed. Think warm lamps and low-tech reading.
• GUT HEALTH: A healthy microbiome plays a role in melatonin production. Eat fermented foods, fibre, and plenty of colourful veg.
• FOOD CHOICES: Cherries, bananas, and oats, all naturally support melatonin production.

I think it’s best to avoid melatonin supplements, except for helping to manage jet lag. Supplements are not a long-term solution. They’re unregulated in many markets, and dosages can differ greatly between what’s on the label, and what's in the pill.

To sum it up, achieving great sleep is about your whole day. It's actually less about your nighttime routine, and more about your daytime routine. 

• Get morning sunlight to regulate cortisol, serotonin, and adenosine.
• Be consistent with your wake-time. Your body will know when to produce these chemicals based on your routine.
• Stay active and eat well.
• Embrace darkness in the evening.

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