Lack of sleep can leave you 'functionally drunk' – Experts

Failing to get enough sleep can leave a person “functionally drunk”, in a matter of days, experts today warned.

They note sleep is much more important than many people realise.

Even if a person achieves six hours a night, they are building up a sleep debt, Olivia Walch from the University of Michigan said.

Her warnings come as a new study, co-authored by Ms Walch, reveal the sleep patterns of people across the world.

The findings show middle-aged men are the most likely to be sleep deprived, often failing to get the recommended seven to eight hours shut eye.

Researchers found women are more concerned with scheduling their sleep, planning around 30 minutes more a night, on average than their male counterparts.

Women tend to go to bed earlier and wake up later, especially those aged between 30 and 60, the study found.

Those people who spend time in sunlight each day tend to go to bed earlier and get more sleep than those people who spend most of their time cooped up inside all day.

Ms Walch said: “It doesn't take that many days of not getting enough sleep before you're functionally drunk.

“Researchers have figured out that being overly tired can have that effect.

“And what's terrifying at the same time is that people think they're performing tasks way better than they are.

“Your performance drops off but your perception of your performance doesn't.”

Researchers collated their data using a free smartphone app that helps reduce jetlag.

It allowed them to gather robust sleep data from thousands of people across 100 countries. The researchers examined how age, gender, the amount of light and home country affect the number of hours sleep people around the globe get each night.

They also looked at when people went to bed, and when their alarms go off in the morning.

Researchers found that cultural pressures can override natural circadian rhythms, with the effects being most markedly seen at bedtime.

While morning responsibilities, such as work, children and school, play a role in a person's wake-time, the researchers said they are not the only factors.

Dr Daniel Forger, who also took part in the study, said: 'Across the board, it appears that society governs bedtime and one's internal clock governs wake time, and a later bedtime is linked to loss of sleep.

“At the same time, we found a strong wake-time effect from users' biological clocks - not just their alarm clocks.

“These findings can help to quantify the tug-of-war between solar and social timekeeping.”

When Dr Forger talks about internal or biological clocks, he's referring to circadian rhythms -fluctuations in bodily functions and behaviours that are tied to the planet's 24-hour day.

These rhythms are set by a grain-of-rice-sized cluster of 20,000 neurons behind the eyes.

They are regulated by the amount of light, particularly sunlight, our eyes take in.

Circadian rhythms have long been thought to be the primary driver of sleep schedules, even since the advent of artificial light and 9-to-5 work schedules.

The new research helps to quantify the role that society plays.

Dr Forger, Ms Walch and their team released an app called Entrain, several years ago.

It is designed to help travellers adjust to new time zones, and recommends custom schedules of light and darkness.

To use the app, a person has to enter their typical hours of sleep and light exposure, and users are also given the option of submitting information anonymously to the University of Michigan's research team.

The quality of the app's recommendations depended on the accuracy of the users' information, and the researchers say this motivated users to be particularly careful in reporting their lighting history and sleep habits.

With information from thousands of people in hand, the researchers then analysed it for patterns.

Any correlations that bubbled up, they put to the test in what amounts to a circadian rhythm simulator.

The simulator - a mathematical model - is based on the field's deep knowledge of how light affects the brain's suprachiasmatic nucleus - the cluster of neurons behind the eyes that regulates our internal clocks.

With the model, the researchers could dial the sun up and down at will to see if the correlations still held in extreme conditions.

“In the real world, bedtime doesn't behave how it does in our model universe,” Ms Walch said. “What the model is missing is how society affects that.”

The spread of national averages of sleep duration ranged from a minimum of around seven hours, 24 minutes of sleep for residents of Singapore and Japan to a maximum of eight hours, 12 minutes for those in the Netherlands.

That's not a huge window, but the researchers say every half hour of sleep makes a big difference in terms of cognitive function and long-term health.

The findings, the researchers say, point to an important lever for the sleep-deprived - a group of people that the Centres for Disease Control and Prevention is concerned about.

A recent CDC study found that across the US, one in three adults aren't getting the recommended minimum of seven hours.

Sleep deprivation, the CDC says, increases the risk of obesity, diabetes, high blood pressure, heart disease, stroke and stress.