You’ve seen it glaring on your sleep tracker - how much deep sleep you got last night. However without giving this number some context, you might not realize just how foundational this specific stage of sleep is to your health, energy, and performance.
This particular metric isn’t just a nice-to-have. Deep sleep is so important because it is when your body shifts into its most powerful recovery mode. If you're shortchanging it, you're leaving muscle gains, mental clarity, and resilience on the table.
Here’s what makes deep sleep non-negotiable - and how to get more of it, starting tonight.
What Happens During Deep Sleep?
Deep sleep, also known as slow-wave sleep, is the third stage of non-REM sleep. It makes up roughly 15–25% of total sleep time in healthy adults, occurring mostly in the first half of the night. During this critical window - while you’re “deep asleep” - your body is actually hard at work rebuilding.
Here’s a look at the essential work happening under the hood:
1. Cellular Repair: Deep sleep is when your pituitary gland releases a surge of Human Growth Hormone (HGH), which is essential for repairing tissues, rebuilding bones, and stimulating muscle growth. This is where your training translates into adaptation.
2. Deep Cleaning the Brain: The brain’s glymphatic system becomes highly active, flushing out metabolic waste and toxins like beta-amyloid that accumulate during waking hours. This process is vital for long-term brain health and next-day cognitive function.
3. Resetting Your Systems: Your heart rate and blood pressure drop to their lowest levels, giving your cardiovascular system a much-needed rest. Your immune system also gets a boost, producing proteins that help you fight off infection and reduce inflammation.
The consequences of missing out are immediate. One study in the journal Diabetes Care found that just one night of reduced deep sleep increased insulin resistance in healthy adults - a key precursor to metabolic issues and weight gain.
6 Science-Backed Ways to Increase Deep Sleep
As neuroscientist and U.S. Army performance coach Dr. Allison Brager puts it, “Optimizing for deep sleep isn’t just about feeling rested - it’s where your body rebuilds. If you’re training hard, this is your competitive edge.”
Tracking your numbers is a great start. But if they're lagging, here’s how to take action:
1. Drop Your Temperature: Your body’s core temperature needs to drop to initiate and maintain deep sleep. You can accelerate this process by keeping your bedroom cool, aiming for 60–67°F (15–19°C).
2. Chase the Morning Sun: Exposure to natural sunlight for 15-20 minutes within the first hour of waking is one of the most effective ways to strengthen your circadian rhythm. A robust internal clock leads to a stronger buildup of sleep pressure (adenosine) throughout the day, promoting deeper sleep at night.
3. Be Strategic With Alcohol: While alcohol can make you feel sleepy, it significantly disrupts sleep architecture later in the night. Research shows that even a single drink can suppress deep sleep. If you choose to drink, try to finish at least three hours before bedtime.
4. Fuel for Recovery at Dinner: A balanced final meal can support the restorative processes of deep sleep. A combination of slow-digesting carbohydrates (like sweet potatoes or quinoa) and quality protein helps facilitate the uptake of tryptophan while providing the amino acids needed for muscle repair.
5. Consider Magnesium: Magnesium plays a key role in calming the nervous system by regulating the neurotransmitter GABA. Studies have shown that supplementation, particularly in those with insufficient levels, can improve sleep quality and increase time spent in slow-wave sleep. Lagoon offers a magnesium citrate supplement available here.
6. Eliminate Micro-Awakenings: The less you move, the more time you can spend in uninterrupted deep sleep. A pillow that is properly aligned with your sleep style and body type is critical for preventing the position changes and micro-awakenings that pull you out of essential sleep cycles.
It’s About Stacking Habits, Not Chasing Perfection
Getting more deep sleep is all about stacking the conditions in your favor. As Dr. Rafael Pelayo, Clinical Professor of Sleep Medicine at Stanford so aptly puts it “When we improve deep sleep, we improve the foundation of everything else - mood, memory, metabolism, and immunity.”
And while you don’t need a perfect score, you can always make some improvements. Start with an achievable goal: try to increase your deep sleep time by just 10% over the next month. For most people, that’s only 6–10 extra minutes a night.
Track what works, refine your routine, and give your body the powerful restoration it’s asking for.
