How much sleep do we really need ?

How Much Sleep Do We Really Need?

How much sleep do we really need ?

Why do we sleep?


"The only known function of sleep is to cure sleepiness', This isn't quite true, but the question of why we spend about a third of our lives asleep and what goes on in our head during this time are far from being solved.
One big mystery is why sleep emerged as an evolutionary strategy. It must confer powerful benefits to balance out the substantial risks, such as being eaten or missing out on food while lying dormant. The emerging picture from research is that sleep is not a luxury but essential to both physical and mental health. But the complex and diverse functions of sleep are only just starting to be uncovered.



What's going on in our brains while we sleep?


How much sleep do we really need ?
The brain doesn't just switch off. It generates two main types of sleep:
Slow wave sleep (deep sleep) - SWS and Rapid eye movement (dreaming).
About 80% of our sleeping is of the SWS variety, which is characterized by slow brain waves, relaxed muscles and slow, deep breathing. There is strong evidence that deep sleep is important for the consolidation of memories, with recent experiences being transferred to long term storage. This doesn't mean happen indiscriminately though - a clearout of the less relevant experiences of the preceding day also appears to take place. A study published last year revealed that the connections between neurons, known as synapses, shrink during sleep, resulting in the weakest connections being pruned away and those experiences forgotten.


Dreaming accounts for the other 20% of our sleeping time and the length of dreams can vary from a few seconds to closer to an hour. Dreams tend to last longer as the night progresses and most are quickly or immediately forgotten. During REM sleep, the brain is highly active, while the body's muscles are paralysed and heart rate increases and breathing can become erratic. Dreaming is also thought to play some role in learning and memory - after new experiences we tend to dream more. But it doesn't seem crucial either: doctors found that one 33-year old man who had little or no REM sleep due to shrapnel injury in his brainstem had no significant memory problems.

How much sleep is enough?


How much sleep do we really need ?
Eight hours is often quoted, but the optimum sleeping time varies between people and at different times of life. In a comprehensive review, in which 18 experts sifted through 320 existing research articles, the US National Sleep Foundation concluded that the ideal amount to sleep is seven to nine hours for adults, and eight to ten hours for teenagers. Younger children require much more, with newborn babies needing up to 17 hours each day (not always aligned with the parental sleep cycle).


However, the experts did not consider quality of sleep or how much was SWS v REM. Some people may survive on less sleep because they sleep well, but below seven hours there was compelling evidence for negative impacts on health. According to experts, too much sleep is also bad, but few people appear to be afflicted by this problem. In the UK the average sleep time is 6.8 hours.

What happens when you don't get enough sleep?


How much sleep do we really need ?
In extreme cases, sleep deprivation can be fatal. Rats that are completely deprived of sleep die within two or three weeks. This experiment hasn't been repeated in humans - obviously - but even a day or two of sleep deprivation can cause otherwise healthy people to suffer hallucinations and physical symptoms. After a poor night's sleep, cognitive abilities take an immediate hit. Concentration and memory are noticeably affected and people are more likely to be impulsive and favour instant gratification over waiting for a better outcome. We are also worse people when we're tired - one study found that sleep deprived people are more likely to cheat and lie.
What about physical health?
How much sleep do we really need ?
Cumulative lack of sleep can have long term health consequences, and links are seen with obesity, diabetes, heart disease and dementia. A review of 28 existing studies found that permanent night shift workers were 29% more likely to develop obesity or become overweight than rotating shift workers. Findings based on more than 2 million individuals found that working night shifts raised the risk of a heart attack or stroke by 41%.


The reasons for some of these associations are complex and hard to separate from other lifestyle factors. The studies mentioned above attempted to filter out socioeconomic factors, for instance, but factors like stress and social isolation can be harder to capture. That said, there is growing evidence for a direct biological influence. Sleep deprivation has been shown to alter the body's basic metabolism and the balance between fat and muscle mass.


Foods that will help you sleep better


Many foods contain naturally occurring substances that bring on sleep. Here are some of the best choices to help you settle down for a quality rest.


Walnuts

How much sleep do we really need ?
Walnuts are good source of tryptophan, a sleep-enhancing amino acid that helps make serotonin and melatonin, the "body clock" hormone that sets your sleep wake cycles. Additionally, University of Texas researchers found that walnuts contain their own source of melatonin, unlike other foods that help you sleep, which may help you fall asleep even faster.


Almonds


How much sleep do we really need ?
Almonds are rich in magnesium, a mineral needed for quality sleep (and for building bones).


Sweet Potato


How much sleep do we really need ?


Sweet potatoes are great source of potassium, magnesium, and calcium to help you relax.


Oatmeal


How much sleep do we really need ?
 It may be a favourite for breakfast, but you might want to pair a bowl of oatmeal with some coffee to make it through the day.
They raise your blood sugar naturally and make you feel sleepy. Oats are also rich in melatonin, which relaxes the body and helps you fall asleep.


Dark chocolates


How much sleep do we really need ?


Don't worry - you can eat chocolate day and night. Dark chocolates contains serotonin, which relaxes your body and mind.


Bananas


How much sleep do we really need ?
The magnesium and potassium in bananas serve as muscle and nerve relaxants. Vitamin B6 found in the fruit also converts tryptophan into serotonin, increasing relaxation even more..



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