How many hours of sleep per night does a human being need to be healthy?
I bet you've answered eight hours,
but that's not quite true according to recent scientific findings.
This is misunderstood.
That's like saying everybody should be five feet ten inches tall
and if you're shorter than 5'10, you've got a problem.
Not all of us need the same amount of sleep to be
well-rested and function at a high level.
And it's not a matter of behaviour or choice.
It's in the genes.
Some people are genetically designed to be what is called 'natural short sleepers'.
This means they only need four to six hours of sleep per night
and still wake up feeling fresh.
Others have called these folks 'elite sleepers', and I think it makes sense.
They get by with much less sleep and still perform at a high level.
And it is true that it is a real asset in today's work world.
For the past 25 years, Dr Ptacek and his team
have been analysing the sleeping patterns of over 100 families.
In the beginning, all of our work was really focused
on trying to figure out what the diagnostic criteria should be
to call someone a 'familial advanced sleep phase' person.
An 'advanced sleeping phase' person is also known as a 'morning lark'.
Someone that goes to bed early and wakes up early.
Some people came to our attention who are extreme morning larks,
but who stayed up too late to meet our criteria.
It became clear to us then that there were families that were morning larks,
yes, but they were also night owls. And that's when we had this idea that
perhaps these families have something different and that is 'natural short sleep'.
That allows them to wake up early and to stay up late.
So far, four genes related to 'natural short sleep' were identified.
But it's likely to be more.
The challenge is – these genes are quite rare.
Dr Ptacek estimates that only one person in a thousand is an 'elite sleeper'.
The good news is that they might unlock the secrets
in sleep efficiency for all of us.
We have a very strong impression that these folks are healthier than average.
We have measured, using questionnaires,
measured people's resilience and 'natural short sleep' groups
scored much higher on the resilience scales than non-short sleepers.
These people are sleeping so much less
and they're still doing well, that maybe they're sleeping more efficiently.
And then the question is: 'What does that mean?'
We might be getting closer to this answer.
In a new study, 'natural short sleep' genes were introduced
in mice with Alzheimer's disease,
and the animals became more resilient.
This is very exciting because it suggests
that we might be able to target that biology for therapeutic use, not just
with regard to neurodegenerative diseases,
but psychiatric diseases, diabetes,
obesity, many cancers.
I view this as a large jigsaw puzzle.
There's a picture of sleep in a jigsaw puzzle,
but we don't know what the picture is. So what we've got is these families, and
in every family where we can identify a gene and a genetic variant
and show that it is actually causing that trait.
We're still very much in a discovery process trying
to find as many pieces to the puzzle as we can.
For something that most of us spend a third of our lives doing,
there's still a lot to understand about sleep.
Something is happening when we're sleeping that allows
us to restore our functions, to wake up the next day and perform well.
If we could do that better by understanding how sleep efficiency
is regulated, then we think this could have a huge impact on human health.