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Most people spend almost ⅓ of their lives in bed, and the amount of sleep we get can have a huge effect on our concentration, memory, stress levels and other areas of our waking lives. Young children might need up to 12 hours of sleep a day, while Margaret Thatcher famously got by on 4. So what is the optimal amount of shut eye to get of an evening? Here we take a look at the existing evidence.
Many studies have shown that the amount we sleep has changed significantly over the last centuries; a trend which can be traced back to the Industrial Revolution. Since then there has been a societal shift in the way we view sleep - less a necessity, more a luxury to be easily sacrificed. However, according to Britain’s NHS having too little sleep will fog your decision making and is associated with high blood pressure, heart disease and diabetes.
But sleeping too much also has associated health concerns. Those who sleep 9 or more hours have higher levels of obesity and depression and also heart disease and diabetes, which seems like a real case of damned if you do, damned if you don’t!
Of course the amount an individual needs to sleep is largely an individual trait, which will change throughout your life. Although it may not feel that way to parents, newborn babies sleep on average 18 hours out of 24; whereas the elderly may need only 5-6. Factors like diet, exercise and metabolism will also weigh heavily on how much sleep feels natural to you.
For adults the benchmark figure for sleep has long been 8 hours - advice provided by reputable bodies like the US Center for Disease Control (CDC). New long term research has cast doubt on that assumption however and a study from Arizona State University recently showed that adults sleeping between 6.5 to 7.4 hours a night showed the lowest levels of health problems.
Sleep, as we describe it, can actually be broken down into several common phases. The most commonly discussed of which are “slow wave” and “rapid eye movement” (REM). During deep sleep the body transfers memories from short term to long term storage, and if this isn’t done quickly you won’t form long term memories. Slow wave sleep tends to occur deep into your sleep cycle; so if you’re preparing for an exam or memory intensive task you’d be well advised to get a long rest.
REM sleep, on the other hand, is associated with problem solving and creativity, and you will experience some REM sleep during naps. As we discussed in another article, napping during the day can help replenish your faculties and problem solving ability.
Many sources will tell you its possible to train yourself to sleep less, and the US Military even has a “sleep reduction program”. While it may be true that many can lose an hour’s sleep with no ill effects; attempting to push your regular sleep hours far below your natural levels is very likely to end in stress, diminished capacities and even long term health problems.
Sleep isn’t a luxury, or “time wasted”, it is vital to the health of both body and brain. If you’re looking to develop healthier sleep patterns, check out our discussion of sleep promoting foods or experiment with changing your sleep routine. As many of us already sleep close to our natural level cutting back on sleep - by as little as 20 minutes, can have measurable impacts on performance. If you ever find yourself groggy and unable to concentrate in the mornings remember there is no magic remedy - just try and get a bit more kip the next evening!