How to set up your energy, focus and resilience in 90 minutes a night

Sleep is the foundation of our physical health, mental health, physical performance and cognitive performance.

Since the work of sleep researcher and book author Prof. Matthew Walker became popular, many more people are getting 7 or 8 hours of sleep each night. However, even when we get that full night’s sleep, we often feel groggy in the morning and tired throughout the day.

The reason is that how we sleep is as important as how much we sleep. If you want to set your energy, focus and resilience up for the long term, getting sufficient quality sleep should be one of your top priorities. This is due to two reasons.

First, quality sleep is the ultimate way to recharge our mental energy and focus. When we lack sufficient quality sleep, our working memory performance plummets by approximately 60 percent. This leads to a decrease in productivity, especially when we try to focus on something complex. Without sufficient sleep, doing cognitively challenging tasks can take more than twice as long. In “Why We Sleep”, Matthew Walker offers a compelling analogy to illustrate this notion: “Why try to boil a pot of water on medium heat when you could do so in half the time on high?” Conversely, getting plenty of high-quality shut-eye can increase our productivity by up to 150%. If we start our days well-rested, we can crank up the heat to accomplish more in less time.

Second, quality sleep plays a crucial role in high-stress environments – because it prevents acute stress from turning into chronic stress. According to Prof. Andrew Huberman, the most reliable warning signal of moving from acute stress to chronic stress shows up in our sleep: “When you are no longer able to achieve good sleep, you are now moving from acute stress to chronic stress”. Sleep and stress share a reciprocal relationship, with excessive stress undermining sleep quality, and insufficient high-quality sleep diminishing our resilience. It’s a vicious cycle. 

However, even in the midst of high-stress periods, we can turn this vicious cycle into a virtuous one – by prioritizing sufficient high-quality sleep on a consistent basis. 

Doing that is easier than you think. As it turns out, focus and sleep are really similar: During the day, spending about 90 minutes in the deeply focused “flow state” roughly doubles your overall productivity, according to research by McKinsey & Company. And at the literal end of the day, it also comes down to having spent sufficient time in the “deep end”. 

Apart from light sleep and rapid-eye-movement (REM) sleep, deep sleep is one of the sleep stages we go through multiple times throughout the night. As the name suggests, it’s a stage from which we’re not easily woken up. More importantly, deep sleep is the most restorative and rejuvenating sleep stage. According to Walker, it “[…] allows our bodies, particularly our brains, to refresh and repair to maintain physical and mental health”. It’s during deep sleep when our body repairs and restores its systems, from our muscles to our brain. As a result, deep sleep is vital not only for our health, but also for optimal physical and mental performance.

If you’re wondering how much deep sleep you need in order to get all these benefits, I’ve got good and bad news for you. The good news first: No matter how many hours you sleep, it all comes down to getting just about 90 minutes of deep sleep per night. Again, focus and sleep are very similar in that regard. By spending 90 minutes in the most restorative and rejuvenating sleep stage per night, you’ll get all the recovery that your body and brain need to be at their best throughout your waking life. And as you can see in this hypnogram of an ideal night, we get our 90 minutes of deep sleep mostly within the first half of the night: 

This brings us to the bad news: If you often feel tired in the morning and throughout the day despite getting 7-8 hours of sleep, you’re probably not getting these 90 minutes of deep sleep. As it turns out, you’re not alone. Only 15 percent of us wake up from our sleep feeling refreshed. If that sounds like you, you’re probably not spending enough of that first half in the “deep end”, but in the “shallow end” instead – mostly in light sleep, that is.

In the remainder of this post, you’ll get the essential knowledge and practices to move from mostly shallow to sufficient deep sleep each night.

While going about our day is like driving a car – where we need to use both the accelerator and brake if we want to go reasonably fast (read: be productive and perform well) without ending up in a crash (read: suffer from exhaustion or burnout) – getting sufficient deep sleep each night is more akin to landing a plane. 

There are three crucial steps for pulling of the landing of that metaphorical plane. These are preparing the descent (setting up your system for deep sleep), setting up the landing strip (the bedroom), and touching ground (falling asleep). 

Preparing the descent

If getting 90 minutes of deep sleep a night resembles landing a plane, the first step includes setting up that plane for its descent. As it turns out, this comes down to the three T's of preparing your system for deep sleep throughout the day: timing, time givers, and technology. 

1) Timing
The first T is timing. We’ll start with a low-hanging fruit that might transform your energy levels after waking up by tomorrow. Recall that we go through different stages of sleep – light sleep, rapid eye movement (REM) sleep, and deep sleep – in cycles of 90 minutes. As it turns out, when we’re woken up in the middle of one of these cycles, we experience what scientists call "sleep inertia". When this happens, we feel groggy in the morning and even tired throughout the day. The remedy is simple and easy: Set your alarm so that you sleep in multiples of 90 minutes by going for 6, 7.5 or 9 hours – instead of 7 or 8 hours.

Apart from (not) sleeping in multiple of 90 minutes, the timing of our sleep across days can make or break your nights: One of the best ways to ensure sufficient deep sleep in the first half of the night is to wake up and go to bed at the same time throughout the week. Conversely, if you want to sleep well at night and be at our best each day throughout the week, sleeping in on weekends is a terrible idea: Your circadian rhythm is guided by our wake-up time rather than our bedtime. As a result, irregular wake-up times – most notably sleeping in on the weekend – produce symptoms similar to what jetlag feels like.

That’s why sleep scientists also call this phenomenon social jetlag: As a result of just one or two days of sleeping in, we’re tired at awkward times throughout our days and have difficulties falling asleep in the evenings for the rest of the week. Social jetlag is one of the biggest obstacles to getting sufficient deep sleep. Adding to the problem, most of us go to bed at the same time each day and vary our wake-up time based on how we feel when we wake up. As it turns out, that’s precisely the opposite of what we should do.

As Prof. Matthew Walker has put it, “regularity is king”. The best way to ensure sufficient deep sleep in the first half of the night is to wake up and go to bed at the same time throughout the week, including on weekends. Here’s how to pull that off:

1. Find your regular wake-up time. Think about the last four weeks of your life. Then, without considering irregular activities like catching a red-eye flight, determine the earliest time you had to get up. Et voilà, that time is your regular wake-up time. For me, it’s 6 am.

2. Sleep for five 90-minute cycles. Sleep in multiples of 90 minutes to avoid sleep inertia. For the benefits of both deep sleep and other stages of sleep, go for five of these cycles (or 7.5 hours). If you need to work late or want to stay awake longer for other reasons, don’t worry about doing so occasionally – but still try to go for at least four cycles (or 6.0 hours). I opt for 7.5 hours most nights.

3. Find your regular bedtime. Take your regular wake-up time and subtract the number of hours that you want to sleep. On top of that, subtract the time it usually takes you to fall asleep. For most of us, that’s between 5 and 15 minutes. The result of that calculation is your regular bedtime. For me, that’s 10.20 pm (06.00 am - 7.5 hours - 10 minutes).

Then, set your alarm to your regular wake-up time on each day of the week. Maintain that wake-up time on the weekends without deviating more than 15 minutes. 

2) Time Givers
The second T relates to the three major time givers: light, nutrition and exercise. As I’ve explained in earlier posts, these are key for optimizing your circadian rhythm and sleep pressure.

I won’t go into the underlying mechanisms because that would double the length of this post. If you want to learn about them, follow the links included in the next paragraphs. For now, here are my two simple rules for setting your circadian rhythm and sleep pressure up for 90 minutes of deep sleep at night.

First, follow the 10-10-10 rule for optimizing the timing of your light viewing throughout the day. Get 10 minutes of sunlight into your eyes before 10 am and avoid bright (blue) light after 10 pm. 

Second, adhere to the 3-3-3 rule for optimizing the timing of your exercise and nutrition throughout the day. Avoid intense exercise three hours before bedtime, have your last meal three hours before bedtime, and stay away from caffeine after 3 pm.

3) Technology
Whether or not you choose to do a shutdown ritual in the evening, being deliberate about how you use the third T – technology – in the evening is key for getting the deep sleep you need in the first half of the night.

In “The 3 Alarms”, my co-author and CEO coach Eric Partaker shares a practice that’s very simple and effective for pulling this off: The “digital sunset”. It works as follows: One hour before your regular bedtime, shut off all the electronics, most notably your computer and smartphone. E-readers are okay, given that you dim the light on them.

Doing that has two major advantages for getting the deep sleep you need. First, it prevents blue light from confusing your circadian master clock. This clock mistakes this kind of light for sunlight late in the day. Our brain then thinks that it’s daytime, which makes it impossible to get the deep sleep we need during the first half of the night.

Second, a digital sunset enables your brain to step on the brake. That brake is located in the “parasympathetic nervous system”, or calmness system. When active, this system makes us calm. As it turns out, getting into deep sleep requires a strong activation of that system. Staying away from both work-related and leisure-related stressors by disconnecting fully one hour before bed goes a long way to letting our calmness system do its magic in time.

Setting up the landing strip

Congratulations, you’ve almost made it! After you’ve eliminated sleep inertia and social jetlag, synchronized your brain by optimizing the major time givers, and committed to performing a digital sunset one hour before your regular bedtime, you’ve done all it takes to prepare the plane for a safe, smooth landing.

Now, when it comes to landing the plane, preparing the airstrip right is very important. This airstrip is your bedroom. So go with the recommendation of the American Academy of Sleep Medicine and turn your bedroom into a cave: It should be dark, quiet and cool. Here’s why and how.

1. Your bedroom should be dark. Although you won't notice it, even small amounts of light go through your closed eyelids. While you sleep, this decreases activation in your sympathetic autonomic nervous system, which prevents you from getting the deep sleep you need in the first half of the night.

2. Your bedroom should be quiet. As it turns out, we're very sensitive to noise when we're asleep – and that noise doesn't have to be loud, let alone wake us up. Even minor acoustic disturbances – your neighbors talking to each other, say – reduce activation in the parasympathetic arm of your autonomic nervous system, similar to light. That's why noise keeps you from getting into deep sleep. 

3. Your bedroom should be cool. Your body needs to drop its core temperature by 1 to 1.5 degrees Celsius to get into deep sleep in time. The general recommendation is a room temperature between 18 and 22 degrees Celsius; the closer to 18 degrees you can tolerate, the better. But don't worry: You don't have to freeze. Feel free to use as many sheets as you need.

Touching ground

Now, after preparing both the plane and the airstrip for a smooth landing, you’ve gone all the way to prepare for a great night of slumber. The last step is all about touching ground. This includes falling asleep at the beginning of the night and falling back asleep throughout it whenever you wake up. So let’s have a look at the most effective techniques for doing just that.

When it comes to falling asleep, remember that it usually takes us between 5 and 15 minutes to do so. On some nights, though, pulling that off can be difficult. Maybe you've had a stressful day at work, or you're worried about something in your private life. When that happens, trying to control your mind with your mind often backfires. As you’ve learned in last week’s post, a better way is to use breathing to calm yourself down.

When you exhale more than you inhale, you slow down your heart and trigger the calmness system in real-time. So to fall asleep, both the physiological sigh and three-six breathing work greatly to support your transition into sleep at night. Doing three rounds of physiological sighing or four or five rounds of exhale-emphasized breathing will make falling asleep much, much easier, even after a very busy and stressful day. 

In terms of staying asleep at night, there’s one important scientific fact to consider: Pulling that off is impossible. Waking up multiple times during the night, it turns out, is entirely normal. As you can see in the hypnogram included above, we go through numerous 90-minute sleep cycles and wake up between them – at least very briefly. This often happens unconsciously, and we go right back to sleep without even remembering it the next morning. Whenever you consciously wake up during the night and want to fall back asleep, it all comes down to what you do next. Here are three essential tips. 

1. Try to avoid bright, overhead lights. Again, your brain mistakes light that is bright or comes from above for sunlight. That's why viewing it at night will make it harder for you to fall back asleep. If you need to use the bathroom, try to use dim and lowly set lights instead of bright, overhead ones.

2. Stay away from your smartphone. Similar to bright, overhead lights, blue light from your smartphone will make it hard to fall back asleep. Also, checking your messages and social media feeds will activate your "alertness system" and deactivate your “calmness system”, which makes falling back asleep even more challenging.

3. Don't stress out over the fact that you're awake. Whenever you wake up in the very early morning hours, don't get caught up in the fact that you should be sleeping. Recall the figure above and that you've probably had most of the deep sleep you need during the first couple of cycles. Not getting the rest of the night perfect won't matter all that much. Thus, consider that rest of the night as a bonus – and again use the tips described above for falling asleep.

That’s it. You just learned how to set up your energy, focus and resilience in 90 minutes a night – without sleeping a minute longer. You’re welcome.

TL;DR

1) We can set up the foundation of our health and performance by getting 90 minutes of deep sleep per night, which is like landing a plane – and starts with setting that plane up for the “descent” with the three T’s of timing, time givers and technology

2) Optimize your timing by sleeping in multiples of 90 minutes (to avoid sleep inertia) and maintaining a regular wake-up time each day of the week (to prevent social jetlag)

3) Leverage the three time givers light, exercise and nutrition by following two simple rules: the 10-10-10 rule for light and the 3-3-3 rule for exercise and nutrition

4) Be deliberate about technology in the evening by doing a “digital sunset” one hour before your regular bedtime – and shut off your computer and smartphone 

5) Prepare your metaphorical “landing strip” by turning your bedroom into a cave that is dark, quiet and cool

6) “Touch ground” and fall (back) asleep by exhale-emphasized breathing, avoiding bright, overhead lights and staying away from your smartphone

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Until next week,
Christian