Matthew Walker

No one would look at an infant baby asleep, and say 'What a lazy baby!' We know sleeping is non-negotiable for a baby. But that notion is quickly abandoned.

If you were not to set an alarm clock, would you sleep past it? If the answer is yes, then there is clearly more sleep that is needed.

Sleep is the Swiss army knife of health. When sleep is deficient, there is sickness and disease. And when sleep is abundant, there is vitality and health.

If we didn't need eight hours of sleep and could survive on six, Mother Nature would have done away with 25 percent of our sleep time millions of years ago. Because when you think about it, sleep is an idiotic thing to do.

Regularity is a key: going to bed at the same time, waking up at the same time no matter what. But I think, also, it's not just about quantity - that's what we've been discovering. It's also about quality.

You're trying to sleep off a debt that you've lumbered your brain and body with during the week, and wouldn't it be lovely if sleep worked like that? Sadly, it doesn't. Sleep is not like the bank, so you can't accumulate a debt and then try and pay it off at a later point in time.

As you try to tweak your sleep one way or the other, you might be, you might be doing great - you might do better at remembering details of an event, but you might end up being poorer at abstracting the gist or the rules associated with it.

Our circadian biology, and the insatiable early-morning demands of a post-industrial way of life, denies us the sleep we vitally need.

I think sleep is probably the neglected stepsister in the health conversation today. I think we've done a good job regarding physical activity and diet, but sleep has remained out there in the cold, and that's surprising to me.

It's during dream sleep where we start to actually take the sting out of difficult, even traumatic, emotional experiences that we've been having. And sleep almost divorces that emotional, bitter rind from the memory experiences that we've had during the day.

Deep non-REM sleep almost hits the save button on those recently acquired informational pieces so that when you wake up the next morning, you have remembering rather than forgetting.

People dramatically underestimate how much sleep is linked to all the diseases killing us. We know a lack of sleep is linked to numerous forms of cancer - bowel, prostate, breast cancer.

You should not actually stay in bed for very long awake, because your brain is this remarkably associative device, and it quickly learns that the bed is about being awake. So you should go to another room - a room that's dim. Just read a book - no screens, no phones - and, only when you're sleepy, return to the bed.

Based on the science, you can make somewhat clear statements: The number of people who can survive on six hours of sleep without impairment is zero.

We know that efficiency and effectiveness are increased when you're getting sufficient sleep, and it will take you longer to do the same thing on an underslept brain, which means you end up having to stay awake longer. So goes the vicious cycle.