MATTHEW WALKER

Many business leaders still believe that time on-task equates to productivity. Even in the industrial era of rote factory work, this was untrue. It is a misguided fallacy, and an expensive one, too. Every key facet required for business success will fail when sleep becomes short within an organisation.

Your subjective sense of how well you're doing under conditions of sleep deprivation is a miserable predictor of, objectively, how you actually are doing.

No aspect of our biology is left unscathed by sleep deprivation. It sinks down into every possible nook and cranny. And yet no one is doing anything about it.

Some people actually sleep better when the significant other is with them. For other couples, it's the opposite.

I think we perhaps are, with sleep, where we were with smoking about 50 years ago, in that we had all of the science, and it was right there for the public discussion, but it's not yet adequately sort of percolated out into policy or even just public wisdom.

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.

Dream sleep provides a fascinating neurochemical soothing balm. It is during dream sleep and only during dream sleep when our brain shuts off a stress-related neurochemical called noradrenalin.

I think the first general point to make from epidemiological studies across millions of people is the following - that short sleep predicts a shorter life. It predicts all cause mortality.

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.

Stay away from screens, especially those LED screens. Those blue-light emitting devices fool your brain into thinking that it's still daytime, even though it's night-time and you want to get to sleep.

What is dreaming, and what happens, and are there any real benefits to dreaming? Well, to take a step back, I think it's important to note that dreaming essentially is a time when we all become flagrantly psychotic.

It's not clear whether the brain actually is designed to have nightmares or whether this is actually the process going awry.

When I give lectures, people will wait behind until there is no one around and then tell me quietly, 'I seem to be one of those people who need eight or nine hours' sleep.' It's embarrassing to say it in public.

Sleep-deprived individuals also generate fewer and less accurate solutions to problems.

Friends say, 'Shall we go out to dinner at 8?' I say, 'I can't, I'm a 10 A.M.-till-6:30 P.M. kind of guy.' I keep that very regular, no matter what.

The gross demonstration of caffeine is that it prevents you from falling asleep. The slightly more nefarious aspect of caffeine is that maybe you can fall asleep, but we know that the depth of deep sleep you're getting if caffeine is still in your system is severely less.

Falling asleep is like landing a plane. It takes time. You've got to sort of gradually descend. I think one of the problems with insufficient sleep is people are not very good at predicting how poorly they are doing when they are under-slept.

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.

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.

Creativity is, after all, lauded as the engine of business innovation.

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.

If sleep does not provide a remarkable set of benefits, then it's the biggest mistake the evolutionary process has ever made.

Alcohol is a class of drugs that we call 'the sedatives.' And what you're doing is just knocking your brain out. You're not putting it into natural sleep.

It's not that we simply get old, and memory starts to go, and sleep starts to deteriorate. But those two things actually are significantly interrelated.

My name is Matthew Walker, I am a professor of neuroscience and psychology at the University of California, Berkeley, and I am the author of the book 'Why We Sleep.'