In our fast-paced lives, it can often seem like there aren’t enough hours in the day. There’s not enough time to finish the tasks we have to accomplish at work, not enough time to see friends and family, not enough time to exercise, and certainly not enough time to rest and relax.
To squeeze everything into our jam-packed days, it’s often our sleep that gets compromised. Whether staying up late socialising or getting up early to go into the office, over time, the number of hours spent asleep each night can reduce significantly – often without you noticing it.
How is that possible? In one US-based study*, it was revealed that people generally overestimate their nightly sleep by around 0.8 hours – and for every hour beyond six hours, they overestimate the amount of sleep they’ve had by about half an hour.
Going by this research, even if you think you’re getting a solid seven hours of sleep a night, you may only be getting six. But, does this really matter?
Unfortunately, the importance of sleep is not universally recognised. Not only do some people lack understanding of just how important sleep is for the mind and body, they also don’t recognise how easy it is to suffer from sleep deprivation.
While they may think they are coping well with less sleep, the effect of sleep deprivation could be assaulting almost every aspect of their lives, from their productivity at work, to their safety on the roads, to their relationships with friends and family, and even their health.
Instead of getting the recommended seven to nine hours of sleep per night, it seems many of us are now getting six or less.
According to the inaugural sleep survey by TEMPUR, back in 1942 only 14% of people averaged six hours of sleep or less per night. However, in 2013, those getting six hours of sleep or less each night had risen to 41%.
But this just isn’t enough. A sleep deprivation study**, published in The Journal Sleep, looked at how restricted sleep affected productivity, revealing some interesting results within the group that was restricted to six hours of sleep each night.
In the study, 48 adults were restricted to a maximum of four, six, or eight hours of sleep a night for two weeks, while one group was deprived of sleep for three days straight.
During their awake-time in the lab, participants were tested on their cognitive performance and reaction time every two hours, while also answering questions about their mood and any symptoms they were experiencing.
The results revealed that participants averaging eight hours’ sleep per night showed the highest performance on average, while those sleeping four hours per night performed worse each day. Those restricted to six hours per night seemed to hold up well until Day 10, at which point, cognitive performance fell to the same levels as those who weren’t allowed to sleep at all.
One of the most disturbing findings within that study was that even with declining cognitive performance, participants within the six-hour group didn’t rate their sleepiness as being all that bad.
Even though their productivity and capability was dropping, they didn’t feel like they were lacking in sleep. One reason for this could be the human habit of ‘renorming’.
Renorming means we are only able to compare how we feel today with how we felt yesterday or the day before. So, if we stayed up all night, we would feel significantly worse than we did yesterday.
However, if we were to restrict our sleep to six hours each night, after a certain period of time, we wouldn’t notice how badly we were coping, compare to two weeks previously.
This is one reason why sleep deprivation and sleep deprivation effects can be so dangerous. The effects can increase over time in such a gradual manner that we don’t really notice that anything has changed.
It’s generally recommended that adults have seven to nine hours of sleep each night. That number will vary according to personal needs – in the same way that some adults need a higher calorific intake than others.
However, just as there is a minimum number of calories recommended for good health and wellbeing, there is also a minimum number of hours’ sleep adults should get each night to ensure their body and mind work to full capacity.
Getting less than seven hours of sleep results in marked impairments in both the brain and bodily health. However, between that seven and nine hour sleep range, there are some ways you can tell whether or not you’re getting enough sleep.
* Sleep duration: how well do self-reports reflect objective measures? The CARDIA Sleep Study. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2785092/
** The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. https://www.ncbi.nlm.nih.gov/pubmed/12683469