Sleep influences EVERY aspect of your life. If you're not trying to optimize your sleep, you're losing out on massive improvements to your well-being.

For many years, it wasn't known why sleep was important for human function. Now, there is an ever growing body of evidence that everything from mood (1) and memory (2), to immune function (3) and muscle repair (4) , to hormone balance and metabolism (5) are all heavily influenced by the quality of your sleep. Even the onset of Alzheimer's is directly correlated with the quality of your sleep!

Rather than me just telling you that you should "get better sleep!" (which is totally useless), here are the top 6 scientifically backed ways to optimize the quality of your sleep.

But first, what does "optimal" sleep even mean?

What is "Optimal" Sleep?

The quality of your sleep is based on several factors, including:

1. Time spent asleep

2. Time spent in each stage of sleep

3. Biomarkers while asleep

Let's go into some more detail.

1. Time spent asleep

The "optimal" amount of time spent asleep is largely dependent on your age. More sleep is required during phases of fast physical development (0-19 years old), and less is needed later in life.

For most adults, 7-9 hours of actual sleep time (not just time spent in bed) is optimal (6). The more physical activity or mentally challenging tasks you're doing, the higher up on that range you should be.

Now, you might be thinking "I feel perfectly fine with 5 hours of sleep. I'm in perfect health. Don't worry about me." WRONG. Time and time again, it has been shown that health degrades much quicker in adults getting less than 7 hours of sleep each night. You're not the exception.

2. Time spent in each stage of sleep

There are three main stages of sleep: light sleep, REM sleep, and deep sleep.

Light Sleep: Light sleep serves as the transition between wakefulness and the deeper stages of sleep. This stage is important for memory consolidation, cognitive function, and relaxation of the mind and body. While there is no strict "optimal" amount of time for light sleep, it typically makes up about 50-60% of an adult's total sleep.

REM Sleep: REM (Rapid Eye Movement) sleep is a unique phase of the sleep cycle characterized by rapid movement of the eyes, increased brain activity, and vivid dreams. REM sleep is considered critical for emotional regulation, memory consolidation, and brain development because of the increased brain activity during this phase. Adults typically need about 20-25% of their sleep to be REM, which amounts to around 1-1.5 hours per night.

Deep Sleep: Deep sleep, or slow-wave sleep, is the most restorative phase of sleep. This stage is crucial for physical recovery, immune system function, and growth hormone release, which are vital for tissue repair and health. It also plays a significant role in memory consolidation, particularly for declarative memories (facts and information). For adults, deep sleep should constitute approximately 20-25% of the night's sleep, translating to roughly 1-1.5 hours.

Of course, you aren't going to intuitively know how much of each stage of sleep you got each night. We will talk about measurement devices later in the article.

3. Biomarkers during sleep

A "biomarker" is any objective measure of the state of your body.

Though there are many biomarkers that could be measured, there are three in particular that are indicative of quality sleep: heart rate variability (HRV), resting heart rate (RHR), and body temperature.

Heart Rate Variability (HRV): HRV is the measure of variation between heartbeats, indicating the balance of the autonomic nervous system (more info here). High HRV during sleep is a sign of good recovery and stress resilience, suggesting quality sleep. Low HRV can signify stress or poor sleep quality. Note though that HRV is very different from person to person, and it is more important to look at your age range and the trends in your HRV over time.

Resting Heart Rate (RHR): RHR is the number of heartbeats per minute at rest, with lower rates indicating better cardiovascular health. A declining RHR during sleep points to effective rest, while an elevated RHR may signal sleep disturbances or other health issues such as the onset of a viral or bacterial infection. The optimal RHR range for adults during sleep is 40-60 beats per minute (7).

Body Temperature: A drop in body temperature at night aids sleep onset and deeper sleep stages. Elevated nighttime temperatures can disrupt sleep and would be a sign that the body was busy performing functions other than restorative sleep.

Again, all of these biomarkers aren't something you'd be able to intuitively know, and we'll talk about measurement later in the article.

The 6 Proven Tips for Optimal Sleep

Now that we know what it means to get "optimal" sleep, let's talk about the scientifically backed ways you can improve the quality of your sleep.

Here are 6 ways you can improve the quality of your sleep:

1. Sun exposure early in the day

2. Not eating or drinking before bed

3. Lowering core body temp

4. Limit blue light before bed

5. Create an environment free of noise or light

6. Go to bed and wake up at consistent times

Let's dive in.

1. Sun exposure early in the day

As you may have heard from Andrew Huberman, getting sun exposure early in the day is very important to set your circadian rhythm in motion (8).

It is recommended that you get 2-30 min of light exposure as early as you can in the day, preferably right when you wake up. Try to get as much exposure as you can on your skin and eyes without staring at the sun directly (duh!).

If you wake up before the sun is out, consider getting a artificial sunlight lamp to have in your bathroom as you get ready in the morning (I like this one).

Additionally, watching the sun set at night will help gear your body for sleep.

2. Not eating or drinking before bed

Eating and drinking before bed can have a big impact on how much deep sleep you attain.

When you eat a meal close to bedtime, your body has to divert resources to digest the food rather than performing normal sleep functions (9). This can cause your core body temperature to rise and will disrupt you from getting deep, restorative sleep.

It is recommended that you avoid food 3 hours before bed.

Drinking large amounts of water can also prevent deep sleep by causing you to need to get up and urinate throughout the night. These disruptions can prevent you from getting into your deeper cycles of sleep and leave you feeling tired.

It is recommended that you consume most of your water early in the day and stop drinking about 2 hours before bed (a few sips thereafter is fine).

3. Lowering core body temp

Your core body temperature needs to drop by about 2 degrees Fahrenheit to get quality sleep (10, 11).

Your body naturally starts to dip in temperature about 2 hours before bed and continues to drop through the night until starting to increase as the morning approaches. This process induces the release of melatonin and sets in motion other processes for quality sleep (12).

Here are a few ways you can assist your body in lowering core temp:

• Schedule your thermostat to drop in temperature a few hours before bed. Ideally your home should be 65 to 68 degrees while you sleep.
• Take a hot bath, shower, or sauna about at least 1 hour before bed. It might seem counterintuitive, but short exposure to heat will cause your core body temp to drop afterwards in order to compensate (13).
• Pat your face/body with room temperature water and sit in front of a fan. The evaporative cooling will cool you off quickly right before bed.
• Poke your feet out of the covers (if you're feeling to hot). This will allow heat to escape.
• You can also get a cooling mattress topper or pillows to help whisk away heat during your sleep. If you want to go all out, check out Eight Sleep (use code CORESAPIEN for $100 off).

If you want more detail and tips on how to lower your core body temperature for sleep, read this article of ours.

4. Limit blue light before bed

Blue light is naturally emitted throughout the day by the sun. Once the sun has set and blue light isn't present, it indicates to the body that it is time to sleep.

However, phones, TV's, and even the ceiling lights in your home emit blue light, making it difficult for your body to keep to its normal circadian rhythm (14).

It is recommended that you reduce the amount of blue light you are exposed to at least two hours before bed, but especially in the last hour.

Here are a few ways you can reduce your blue light exposure:

• Schedule a blue light filter or night-time mode on your phone (instructions for iPhone and Android).
• Get a pair of blue light blocking glasses.
• Dim the lights in your home (or turn off as many as is reasonable) once the sun has set.
• Read a book instead of watching TV or being on your phone close to bedtime.
• Put your phone in another room when you sleep.

5. Create an environment free of noise or light

This one should be pretty self explanatory.

Light and noise will disrupt your sleep, and the more you can do to reduce them, the better your sleep will likely be.

Consider using white noise, black out curtains, and even an eye mask and/or ear plugs to block out as much as possible.

You can also use these light blocking stickers to help block out the pesky lights from electronics.

6. Go to bed and wake up at consistent times

Consistency is your body's way of preparing for sleep and waking up feeling refreshed.

Once your body gets into a rhythm and "knows" what to expect, it will naturally start to regulate your body to lower your body temperature, release melatonin, and relax muscles, all of which will help you get to sleep.

Same goes for waking up at a consistent time. Your body will be able to regulate sleep cycles in a more optimal way when it has a sense of when you will be getting up in the morning.

In fact, keeping to a consistent sleep schedule is Matthew Walker's number one tip from his book "Why We Sleep" (15). Don't underestimate it's power!

A few bonus tips

Adhering to the tips provided above will produce great improvements in the quality of your sleep, but for those who want to go above and beyond, here are a few more:

• Don't work out too close to bedtime. Working out increases your body's core temp.
• Avoid caffeine or nicotine before bed. Should be obvious.
• Avoid alcohol. You may think you get a better sleep with it, but it actually disrupts REM sleep quite significantly (16).
• Avoid stressful conversations or high demand tasks before bed.

Measuring Sleep Quality

Sleep quality is hard to optimize if you can't measure it.

Luckily, every day there are more and more tools to help you measure the quality of your sleep!

Many of them are wearable watches or wrist straps that track sleep data (such as the Apple Watch and WHOOP), others are built into a ring (Oura), and others are built into the bed themself (Eight Sleep).

Though there are many options out there, there is one clear winner in my mind for tracking sleep data: WHOOP.

They have the most comprehensive and detailed sleep data that I've seen on the market. It will track HRV, RHR, oxygen levels, body temperature, motion, and even electrical signals from your body so you know how much light, deep, and REM sleep you got (in a great level of detail!).

On top of this, they provide amazing insights to your workouts, recovery, and how hard you should be pushing in any given day. You can also "talk" to your data through an AI chatbot to get even more insights!

I've been using WHOOP for two years and have absolutely loved it.

(PS Core Sapien is not incentivized to promote WHOOP products.)

Conclusion

Sleep is core to SO much of your well-being.

It influences your memory, immune function, and muscle repair in a way that cannot be ignored.

The sooner you start to optimize it, the sooner you will see it's benefits in your life!