Getting good and enough sleep is scientifically linked to high performance and longevity. Over 20 large-scale studies that have tracked millions of people over decades all report the same relationship: if we sleep well and enough, our cognitive abilities are significantly enhanced, we stay slim, and our risk for diseases are substantially lower, resulting in a longer life. [Walker 2018]

This sheet is structured in two parts: first, you can explore how your sleep works. Second, you get actionable advice on how to get the right amount of high-quality sleep. The reading time of the entire sheet is approximately 4 min.

How your sleep works

Two independent factors dictate how alert and attentive we are when we are awake and how well we sleep: our circadian rhythm and a chemical called adenosine. The former is our “inner clock,” roughly aligned to the 24 h-cycle. The latter is “sleep pressure” that builds up from the moment we are awake.

The distance between the two curves dictates the urge for sleep and wakefulness. They are independent, which is why we sometimes get a “second wind.” The hormone melatonin does not generate sleep itself but signals to these two systems based on darkness and brightness.

Sleep is an active brain state and highly productive. We cycle through two types of sleep: shallow rapid eye movement (REM) sleep, and deep non-REM (NREM) sleep. During REM sleep our brain activity is similar as during wakefulness, but the body is paralyzed. We create new memory associations and we dream. During NREM sleep we move short-term to long-term memory, which is essential for learning.

Each cycle through REM and NREM sleep is about 1.5 h long. The majority of important REM sleep takes place in the last two cycles.

For maximal performance of body and mind, sleep is more important than exercise and diet. The body needs to go through all sleep cycles each night, and there is no shortcut to “sleep faster.” The optimal bedtime is genetically individual, and everybody belongs to one of three chronotypes: 40 % have their peak wakefulness early in the morning, 30 % have it later in the morning, or even in the afternoon, and 30 % lie somewhere in-between. To truly thrive, sleep quality matters even more than our sleep times or quantity. The next two sections offer actionable tactics to optimize both.