18/02/2016 3:44 PM AEDT | Updated 15/07/2016 12:51 PM AEST

Can You Ever Have Too Much Sleep? And Is It Damaging Your Health?

Sleep Research
Ted Spagna via Getty Images
Sleep Research

We all know sleep is good for you, and depriving yourself of those precious zZzs is not good for your health.

But can it go in the opposite direction? Is there such a thing as having too much sleep? And what does that mean for our mental and physical health?

"Sleep is what we term as a self-limiting behaviour," expert in sleep research, Professor Drew Dawson of Central Queensland University, told The Huffington Post Australia.

"Meaning if you have it, you will have it until your body doesn’t need it. The more you do it, the less you want to do it -- it's the same as food and sex.

"Basically we have the equivalent of sleep hunger. If you sleep, you get less hungry.

"When you're tired, your body wants to go to sleep, and when it's had enough sleep, it wakes up. That being said, the general vibe is we are getting less sleep than we used to 100 years ago."

In terms of waking up from an afternoon nap and groggily wondering if you would have been better off without it, Dawson says that has more to do with your struggle to wake up from a deep sleep rather than "over-sleeping".

"People who have had very extended sleep can wake up feeling very groggy and can take a while to wake up," Dawson said.

"It's a bit like when you hear people say, 'I don’t like having a nap because I wake up feeling worse'. Well, they might wake up feeling worse but in 30 minutes time they will be feeling better for having had the nap than without it.

"The exception to that is if there are medical reasons associated with a very long sleep. Narcolepsy is an example of that, but that is pretty rare."

In terms of "morning people" versus "non-morning people," it turns out that is actually a thing, and has to do with how easily you rouse from sleep.

"The process between sleep and wake is not instantaneous. If you have been in a deep sleep, your eyes can be open before your body has completely woken up," Dawson said.

"In the normal scheme of things, you will wake up in the morning, which generally means you will wake up from a light sleep and you wake up relatively quickly.

"That being said, there are differences between people. Some people take longer to transition from sleep to wake -- there is absolutely such a thing as slow wakers and fast wakers -- and there are causes to that as well, the argument being your body clock is either wired earlier or later."


Nodding off at work? You might want to think about getting some more sleep.

However, all this is not to say excessive sleeping should be ignored, or that it doesn't raise any red flags. Dawson points out there are mental conditions as well as physical which could lead to somebody over-sleeping.

"There are some mental health issues which can come into play, for example, depression," Dawson said. "People who are depressed tend to sleep too much.

"However, if you don’t have some kind of mental or psychiatric condition, the amount of sleep you feel like should be in line with what your body actually needs."

Of course, how much sleep your body requires will depend on what you actually need to do throughout the day.

It is this reason Dawson (admittedly controversially) argues the claim we are getting 60 to 90 minutes less sleep than we did 100 years ago, while true, isn't as alarming as it might actually seem.

"I want to preface this with saying this is not a universally held view. In fact, it's very controversial," Dawson said.

"One hundred years ago most of the country worked in farms or made a living by heavily physical work, so they probably did need more sleep than you do now.

"In a sense, the reduction in the amount of sleep we have reflects the nature of work we do and the life we lead and the world we live in. While 100 years ago, you might have needed eight hours sleep, that's not necessarily need what you need today.

"I am certainly not saying everyone gets enough sleep today, but it is a nuanced question."

In terms of how much sleep is too little, Dawson says there is significant research supporting the dangers of not sleeping enough.

"There is well established literature that suggests once your sleep goes down to four hours, there will be significant consequences for that," Dawson said.

"If you sleep for four to five hours, the vast majority of people will struggle. Five to six hours, most people will struggle, but a few people -- maybe one or two percent -- can get by on that.

"Over six hours, most people can survive off that.

"The most popular recommended amount at the moment is an average between seven and eight, but as I said before, there is individual variability as well."