Dr. Guy Leschziner
speaker
55 appearances
1 recordings
1 series
first heard Apr 2025
last heard Apr 2025
Dr. Guy Leschziner’s voice in public audio — every appearance, attributed to the second.
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We know that sleeping very little is associated with a range of negative health consequences, including mortality. People who sleep a very short period certainly have an increased risk of mortality compared to those who sleep seven or eight hours.
Well, I've always been fascinated with sleep. Really, even as a schoolboy, I was fascinated with neuroscience and read the books of Oliver Sacks. And it was really reading those stories that got me fascinated by the world of neurology. And as an undergraduate, although historically in the UK and pretty much everywhere in the world, sleep has been very, very poorly taught.
It's been largely ignored. But as an undergraduate, when I was at Oxford, I was asked to go away and write a thesis on why we dream. And what occurred to me at that point was, first of all, how little we knew about sleep and the fact that despite us doing this for eight hours a day, we have no real understanding of why we do what we do.
It was a really fascinating area that subsequently has taken me into all sorts of areas of medicine because we now understand that sleep and sleep medicine, it has links with every aspect of human physiology and human medicine.
Well, it's staggering, really, if you think about it. If somebody were to ask you, well, why do we eat or why do we drink? And you turned around to them and said, well, you know, I don't know. It would be laughable. Yet this fundamental aspect of our lives is absolutely crucial to every aspect of our being. We really understand incredibly poorly.
I think the answer is that there's no one function of sleep, that sleep has a multitude of functions. So we know that it is...
primarily controlled by the brain and many of its functions are for regulation of brain function of normal brain functioning so that sleep is part of the housekeeping that is required to maintain our brain which is a the most metabolically active organ in our bodies in in fighting shape
We know that sleep has important functions in terms of making connections between different cells within our brain, sometimes actually pruning those connections. But it's also involved in, for example, flushing out toxins or metabolites, substances that have built up over the course of the day out of our brains and back into the rest of our systems.
But it goes well beyond the brain in that we now understand that sleep is absolutely vital for regulation of cardiovascular function, for kidney function, for healing and restoration of various aspects of our bodies, regulation of our immune system and so on. So an absolute array of functions. When we talk about sleep,
Yes, that's absolutely right. I think that some of that is related to the fact that sleep is not a single state. So we often think of sleep and wake as being binary states. So either you're awake or either you're asleep. But actually what we know is that sleep consists of multiple different stages.
So at its most basic level, we divide sleep up into REM sleep or rapid eye movement sleep, where the brain appears to be very active when we monitor the activity of the brain using electrodes on the scalp. Actually, it looks rather similar to wake on that basis. And then non-REM sleep, which is where the brain activity slows down and becomes a little bit more quiescent.
But even within those categories, we know that in non-REM sleep, which is the stage of sleep that we most associate with restorative sleep or sleep that makes you feel better when you wake up.
There are different stages of sleep, and it seems that our experience of sleep, you know, how we subjectively feel our night has gone, sometimes bears relatively little relationship to the objective measurement of sleep that we can record when you come in for a sleep test in a sleep laboratory.
Well, I think on a population basis, we know that sleeping very little or sleeping a lot is associated with a range of negative health consequences, including mortality, the most negative health consequence. So people who sleep a very short period, usually less than about six hours, certainly have an increased risk of mortality compared to those who sleep seven or eight hours.
But it's important to understand that that is on a population basis and that for each individual, what is seen as a normal sleep requirement is perhaps slightly different. And that's a function of the quality of your sleep.
So whether or not you've got anything else going on with your sleep, like, for example, sleep apnea, this breathing condition that disrupts the quality of your sleep because your airway is constantly collapsing. But it's also a function of your genes in that we know that there are a number of genes that influence our sleep requirements.
So, for example, I have a few families that I've seen in whom everybody in that family sleeps a very short duration and doesn't seem to have any negative effects of sleeping, say, four or five hours a night.
But it's also important to understand that some people are resistant to the effects of sleep deprivation in terms of how sleepy they feel, but not necessarily resistant to the effects of sleep deprivation in terms of, for example, their cognitive function, how easy they find to perform particular tasks or how good their memory is, for example.
So just because you don't necessarily feel sleepy when you're sleep deprived doesn't mean that you don't have any consequences of that sleep disruption per se.
Well, the evidence suggests that if you sustain a significant sleep debt, which is how we term it, that if you're losing quite a lot of sleep during the week, then actually it's quite difficult to make that up by lying in at the weekend and that some of those cognitive effects of being sleep deprived during the week persist on a Monday morning.
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