Can I catch up on lost sleep? We ask an expert

Conventional wisdom says that sleepless misery is nothing that a catch-up won't solve. But a new scientific study claims that "sleep debt" can't always be repaid, with some of the damage caused by prolonged sleep deprivation likely irreversible. Do lies make no sense? On a sunny Monday, I asked Professor Derk-Jan Dijk, Director of the University of Surrey Sleep Research Centre.

Did you have a good night ? It wasn't too bad, but studies show that Sunday or Monday is often not good.

Is it just because we worry for work the next day? Yes, but also because most people sleep longer on the weekends. So if you wake up Monday at 6 a.m. with just a few hours of sleep missed — only a little sleep debt — because you napped over the weekend, your brain will keep you awake Monday night. By midweek, you'll have missed even more sleep, so your brain won't let you.

So some sleep debt is useful? Ultimately, there is a payoff between how long you sleep and how long you sleep. you sleep soundly. Not spending enough time in bed is one thing, but another way to induce poor quality sleep is spending too much time in bed. It's about finding the right balance for you.

I honestly think if I found the balance, I wouldn't be able to recognize it anyway. Can't you just tell me what to do? Please? Don't ask me for an easy answer. There isn't.

Isn't that the truth! OK, back to this review – has it put an end to the idea that we can fix our sleep-deprived selves? This study focuses on the neurological consequences of chronic sleep disturbances. It's different from, "Do I have to catch up on my sleep on the weekends?" One study followed more than 43,000 subjects for 13 years to examine sleep duration and mortality. Sleeping less than five hours is a predictor of mortality. But people who are always sleep deprived are different from those who catch up on the weekends. To some extent, weekend sleep can compensate. That's common sense.

Well that's great! Now, in terms of chronic sleep disruption, we see serious negative consequences, such as risk of cognitive decline. But that's not surprising, is it?

I would still like to know more about the limits of sleeping in: if you have a newborn and you are not sleeping, can this damage be repaired? There are mechanisms that allow us to sleep less in certain circumstances. This is also the case in other species, such as migratory birds. I haven't seen any evidence that being a tired mother causes any lasting harm. Studies of night shift workers show cognitive decline, but some recovery is possible once they step away from these shifts.

How long should they walk away? What is the threshold of no return? There are data gaps here. But don't take sleep too seriously. One night of poor sleep will not significantly increase your risk of neurodegenerative disease. If you're feeling good during the day, you shouldn't worry about getting only six and a half hours of sleep.

I admit that I check my Fitbit every morning for see if I slept well. The problem is that we no longer trust each other. If you wake up feeling well rested and alert all day, you have more reliable information from your brain than this Fitbit. Different people need different amounts of sleep. What's important for you to ask is simply, "How am I feeling?"