Matthew Walker

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.

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.

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.

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.

Below seven hours of sleep, there are objective impairments in the body. Eight hours are recommended.

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.

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.

It's simply that older adults don't seem to be able to generate sleep efficiently, and that's why they're not getting it.

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.

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.

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.'

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.