Maybe you've been bingeing a TV show, or decided to stay out for one more drink, and thought to yourself — one night of bad sleep won't matter too much, right?
Wrong. Even just one night of poor sleep can actually have a major impact on your brain, as world-renowned brain surgeon Dr Rahul Jandial explains to 9Honey.
The neuroscientist, who regularly appears on the Today show, says it best in his book Life Lessons From A Brain Surgeon, in which he writes "so essential to life are the myriad activities the brain engages in during sleep that without it, we die."
What happens after one night of bad sleep
"The importance of sleep is undeniable," Dr Jandial says, sharing some of his own experience as a surgical resident.
"When I was in training we stayed up all night. And the next day we would work as well. So we'd go in Monday at 6am and come home Tuesday at 6pm. And that 36-hour shift was made illegal by the American government, because there were errors happening on that second day."
So when asked what happens after just one single night of poor sleep, Dr Jandial says people immediately suffer loss of focus and attention.
"The other thing that goes unrecognised is emotional regulation," he adds. "The way you respond to stress, the way you respond to criticism.
"The way you respond to a difficult situation changes when you're tired, and you've gone without a night of sleep. It can make it harder for you to be balanced and composed.
"And it makes you more irritable as well."
Long-term bad sleep has serious consequences
When it comes to long-term bad sleep, most Australians experience insomnia at some point in their lives, and about 1 in 10 people have at least mild insomnia at any given time.
Over time, a lack of sleep can increase a person's risk of heart problems and stroke. In fact, a 2018 study by McMaster University in Canada, showed sleeping for less than six hours a day increased the risk of stroke by nine per cent.
Dr Jandial says the long-term effects of poor sleep have become especially apparent in shift workers, who are often forced to work against their body's natural circadian rhythm.
"People work graveyard shifts or night shifts, they do have more diseases like diabetes, they do have more heart disease. Something about working at night, gets in the way," he says.
But Dr Jandial also points out a less obvious result of chronic bad sleep.
"What happens to people that have chronic bad sleep is they just get used to under-performing and it becomes a new normal," he explains.
"They're not at their best potential. They're just living in a world of chronic sleep fatigue. So they may not even notice it because that's just how they live."
READ MORE: Is there such a thing as too much sleep?
How long should we sleep?
As explained in Dr Jandial's book, a 2010 analysis of sixteen prior studies involving over 1.3 million people found that those who averaged less than six hours of sleep per night were 12 per cent more likely to die before age sixty-five than those who slept six to eight hours a night.
However, the same study found that people who slept more than nine hours of sleep per night had a 30 per cent increased risk of early death.
Other studies have found all kinds of health risks associated with sleeping too much or too little. The Nurses' Health Study, for instance, found that women who slept more than nine hours per night had a 38 per cent increased risk of heart disease over those who slept eight hours.
And a study from the American Heart Association found that people who already have metabolic syndrome (increased weight, blood sugar, and blood pressure) will double their risk of death if they sleep less than six hours per night.
Of course, the need for sleep varies dramatically over the lifespan, with most babies and toddlers devoting half of each twenty-four-hour period to sleep, while adults over the age of sixty-five do well with as little as seven hours of sleep per night.
Shorter but solid sleep vs longer disrupted sleep
"The conundrum is eight hours of disrupted sleep versus five hours of good sleep," Dr Jandial says.
"And we're finding more and more it's better to have complete sleep with REM and non-REM for five to six hours, rather than lying in bed with disrupted sleep for eight hours.
"This would speak directly to people like myself that are on a pager or take phone calls at night. It also speaks to our teens, who are getting pinged throughout the night. They're in bed for eight hours, but were they disrupted at all?
"And so sleep disruption is actually worse than just having a shorter duration of proper sleep."
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