Sleep is essential for good health. In fact, we need sleep to survive — just like we need food and water. These processes are critical for our overall health. A lot is still unknown about the purpose of sleep. To date, scientists have found that sleep helps the body in several ways.
The most prominent theories and reasons are outlined below. According to the energy conservation theory, we need sleep to conserve energy.
Sleeping allows us to reduce our caloric needs by spending part of our time functioning at a lower metabolism. This concept is backed by the way our metabolic rate drops during sleep. Research suggests that 8 hours of sleep for human beings can produce a daily energy savings of 35 percent over complete wakefulness. The idea is that sleep allows cells to repair and regrow.
This is supported by many important processes that happen during sleep, including:. The brain plasticity theory says sleep is required for brain function. Specifically, it allows your neurons , or nerve cells, to reorganize.
It removes toxic byproducts from your brain, which build up throughout the day. This allows your brain to work well when you wake up. Research suggests that sleep contributes to memory function by converting short-term memories into long-term memories, as well as by erasing, or forgetting, unneeded information that might otherwise clutter the nervous system.
Similarly, sleep is necessary for emotional health. During sleep, brain activity increases in areas that regulate emotion , thereby supporting healthy brain function and emotional stability. One example of how sleep can help regulate emotion occurs in the amygdala. This part of the brain, located in the temporal lobe, is in charge of the fear response.
When you get enough sleep, the amygdala can respond in a more adaptive way. Research shows that sleep and mental health are intertwined.
On the one hand, sleep disturbances can contribute to the onset and progression of mental health issues, but on the other hand, mental health issues can also contribute to sleep disturbances. Sleep affects your weight by controlling hunger hormones. These hormones include ghrelin , which increases appetite, and leptin , which increases the feeling of being full after eating.
Lack of sleep, however, elevates ghrelin and suppresses leptin. This imbalance makes you hungrier, which may increase the risk of eating more calories and gaining weight. Although sleep deprivation affects the immune system and alters hormone levels in the body, its most consistent impacts across animals are in the brain. There is some evidence, in fact, that sleep is just something that neurons do when they're joined in a network.
Even neuron networks grown in lab dishes show stages of activity and inactivity that sort of resemble waking and sleeping , Frank said. That could mean sleep arises naturally when single neurons begin to work together. This could explain why even the simplest organisms show sleep-like behaviors.
Even Caenorhabditis elegans , a tiny worm with only neurons, cycles through quiet, lethargic periods that look like sleep. Perhaps the first simple nervous systems to evolve exhibited these quiet periods, Frank said, and as brains got larger and more complex, the state of inactivity also had to get more complicated.
But the idea that sleep is a natural property of neuron networks doesn't really explain what's going on during sleep. On that front, scientists have a number of theories. One is that sleep restores the brain's energy, according to a review in the journal Sleep Medicine Reviews. During non-REM sleep, the brain consumes only about half the glucose as it does when a person is awake. Glucose is the sugar that cells burn up to release energy.
But if the idea that sleep restores brain energy is true, the relationship between sleep and the brain's energy usage is not straightforward. For example, during sleep deprivation, the brain's breakdown of an energy source called glycogen increases in some parts of the brain but decreases in others. Researchers at Surrey University in Guildford have found that genes involved in inflammation seem to increase their activity. Dr Malcolm von Schantz, who is involved with the Surrey research, believes that the genes are responding to lack of sleep as if the body is under stress.
He speculates that in the distant past in times of stress our ancestors' bodies would prepare themselves for injury by activating these inflammation genes which would cushion the effects of attacks by wild animals or human enemies. In modern times though preparing for an injury that never happens has no beneficial effect - in fact the consequent activation of the immune system might increase the risk of heart disease and stroke.
The expression "half asleep" might be an accurate description of what is going on in the brain when you are feeling slow-witted. Research suggests that parts of the human brain may well be asleep when it is sleep-deprived. Studies on whales and dolphins show that when asleep they continue to use half of their brain to swim and come up to the surface for air. A study on human patients showed that something similar goes on in our brains.
As they became more sleep-deprived, parts of their brain became inactive while they were still awake. What's more the local sleep areas move around the brain.
So although when we go to bed we think one moment we are awake and then there is an abrupt change to sleep - it may well be more of a continuous process. That's a question that psychiatrists, notably Carl Jung and Sigmund Freud, have tried to answer but with limited success. More recently a team at the ATR Computational Neuroscience Laboratories in Kyoto in Japan has begun trying to answer some of these questions by building the beginnings of a dream-reading machine. They asked volunteers to doze off in an MRI scanner and recorded their brain patterns.
The volunteers were then woken up and asked to tell researchers what they were dreaming about. The team then listed 20 separate categories of dream content from these accounts such as dwelling, street, male, female, building or computer screen. The researchers then compared the accounts with the pattern of activity in the area of the brain responsible for processing visual information - and to their amazement they found that there was a correlation.
The device is a very rough tool but it may well be a first step to something that can see in more detail what happens in our dreams and so help researchers learn more about why we dream. It depends on the kid. Larger text size Large text size Regular text size. Did you know: Skipping 1 night's sleep makes a person cranky and clumsy.
After missing 2 nights of sleep, a person will have problems thinking and doing things; his or her brain and body can't do their normal tasks nearly as well.
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