We all have things we would like to believe are true. We’ll eventually be able to afford to buy a house. We wouldn’t really have enjoyed that job we didn’t get. And if we can only get five hours of sleep a night, it won’t do us any harm.

But according to a major new study, that last one is a myth – and it could actually damage our health in the long run.

Researchers at NYU School of Medicine set out to discover which beliefs about sleep were the most widely held, and then scrutinised these ideas against scientific evidence. After reviewing more than 8,000 websites to identify the most common assumptions about sleep, they found that many people subscribe to sleep myths that could be harming their health. 

“Sleep is a vital part of life that affects our productivity, mood, and general health and wellbeing,” said study lead investigator Rebecca Robbins, PhD, a postdoctoral research fellow in the Department of Population Health at NYU Langone Health.

“Dispelling myths about sleep promotes healthier sleep habits which, in turn, promote overall better health.”

The study was published in the journal Sleep Health. Senior investigator Girardin Jean Louis, PhD, a professor in the departments of Population Health and Psychiatry at NYU Langone, said that doctors could “help prevent sleep myths from increasing risks for heart disease, obesity, and diabetes” by discussing sleep habits with their patients.

“Sleep is important to health, and there needs to be greater effort to inform the public regarding this important public health issue,” he said.

Below, we’ve rounded up four of the biggest sleep myths, according to this study. 

You can get by on less than five hours sleep

You’ve probably met at least one person in your life who insisted that they ‘hardly needed any sleep at all’ in order to function properly. Over the years, many prominent figures have boasted of their ability to survive on minimal shut-eye, including former Yahoo CEO Marissa Mayer and Twitter founder Jack Dorsey (both of whom supposedly only need four to six hours a night), fashion designer Tom Ford (three hours a night) and, er, Donald Trump (three to four hours a night).

But the idea that it’s possible to thrive on less than five hours sleep was one of the top myths researchers were able to dispel. In fact, scientific evidence shows that this myth poses the most serious risk to health. Consistently getting less than five hours sleep a night has been linked to illnesses including cardiovascular diseases, such as heart attacks and strokes, and shorter life expectancy.

To avoid the negative effects of this myth, Robbins and her colleagues recommend establishing a consistent sleep schedule and spending at least seven hours asleep each night.

Alcohol before bed helps you sleep

We’re all familiar with the concept of a nightcap. But according to the researchers, a glass of wine or dram of whisky before bed is actively unhealthy for sleep.

According to the studies they reviewed, alcohol reduces the body’s ability to descend into deep sleep, which we need to function properly the next day. 

Snoring isn’t a big deal

If you’re a chronic snorer, don’t write it off as an embarrassing but harmless quirk. While loud snoring can be innocuous, it can also be a sign of sleep apnoea – a potentially serious disorder that causes people to briefly stop breathing while they sleep.

The study authors encourage snorers to check the issue out with their doctor, as sleep apnoea can lead to heart attacks and strokes, as well as other health problems including high blood pressure and an irregular heartbeat. 

Watching TV in bed helps you relax

OK, you probably already knew that dozing off in front of Netflix isn’t a recipe for good sleep. But according to the researchers, we should keep our laptops and TVs out of the bedroom.

Not only do televisions, laptops, smartphones and tablets produce blue light, which can delay the body’s production of the sleep hormone melatonin, the content of what we’re watching can also disrupt our sleep.

“Often if we’re watching the television it’s the nightly news… it’s something that’s going to cause you insomnia or stress right before bed when we’re trying to power down and relax,” Robbins told BBC News.

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