Why 8 hours of sleep is terrible advice and what to do instead (The 3T Method)


85% of people don’t get sufficient quality sleep at night, which kills their productivity and resilience during the day. Fortunately, there’s a simple way to get plenty of high-quality shut-eye – without sleeping a minute longer.

What to do

Instead of merely focusing on 8 hours of total sleep, build the foundation of getting 90 minutes of deep sleep a night — by using the 3T Method.

Why it works

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. In other words, cognitively challenging tasks can take more than twice as long without sufficient quality sleep. In “Why We Sleep”, Prof. Matthew Walker (pictured above) 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%.

Quality sleep also plays a crucial role in high-stress environments. 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. 

Against this background, “8 hours of sleep a night” is as terrible advice as “2000 calories a day”. If you eat junk food (think burgers, fries and soda), you’ll end up sick and miserable. Junk sleep is similar. It looks like the real thing, but lacks the “nutrients” you need. Conversely, a good night’s sleep starts with 90 minutes of deep sleep per night. Deep sleep is the most restorative and rejuvenating sleep stage. According to Prof. Walker, it “[…] allows our bodies, particularly our brains, to refresh and repair to maintain physical and mental health”. During deep sleep, our body repairs and restores its systems, from our muscles to our brain. As you can see in this so-called hypnogram of an ideal night, we get our 90 minutes of deep sleep mostly in the first half of the night:

How to do it

Mastering deep sleep is like landing a plane, which takes three steps: preparing the descent (i.e., setting up your system for deep sleep), setting up the landing strip (i.e., your bedroom), and finally touching ground (i.e., falling asleep). Here’s how to prepare the descent with the 3T Method around time givers, technology and timing.

1) Time givers. To set your system up for sufficient deep sleep in the first half of the night, you need to tell it when it’s day and when it’s night. The three most effective levers (aka “time givers”) for doing just that are light, nutrition and exercise. Use them to set your circadian rhythm and sleep pressure just right. For light, follow my 10-10-10 rule: get 10 minutes of sunlight before 10 am and avoid bright (blue) light after 10 pm. For nutrition and exercise, use the 3-3-3 rule: No caffeine after 3 pm, no food 3 hours before bed, and no intense exercise 3 hours before bed. 

2) Technology. Our devices are arguably the biggest deep sleep killers. One reason is their bright (blue) light. Yet, there’s more to it: devices also crush your deep sleep by making you more alert (or even stressed) at night. That’s why setting boundaries around your devices is crucial. A great way is Intermittent Digital Fasting (IDF). Put your phone out of sight 1 hour before bed (give it its own bedroom!) –  and let it “sleep in” for 1 hour after you wake. You might even turn IDF into a fully-fledged digital sunset by avoiding all screens – computer, TV, iPad – all of ‘em (eReaders are fine).

3) Timing. As Prof. Walker put it, “regularity is king”: the best way to get plenty of deep sleep is to go to bed and wake up at the same time. So keep your bed and wake-up times constant throughout the week. While variations of 30-60 minutes are okay, longer ones reliably kill your deep sleep. Timing sleep right will also let you avoid “sleep inertia”, the grogginess you feel when waking up in the middle of a 90-minute sleep cycle. To avoid this, sleep in 90-minute multiples – by going for 7.5 or 9 (not 7 or 8!) hours of sleep a night. Add 5-15 mins for falling asleep.

Again, getting to 90 minutes of deep sleep is like landing a plane. You’ve just learned how to prepare its descent with the 3T Method.

I’ll share how to set up the landing strip and touch ground over the following weeks.