Читать книгу The Element Encyclopedia of 20,000 Dreams: The Ultimate A–Z to Interpret the Secrets of Your Dreams - Theresa Cheung, Theresa Cheung - Страница 7

‘Sleep is the balm for hurt minds, nature’s great second course.’ William Shakespeare

Sleep is absolutely crucial for our physical, mental and emotional health and well-being. It is during sleep that we abandon conscious control of our physical body and the unconscious mind is allowed to roam free, giving rise to dreams.

Although we now know a lot more about dreams, their real purpose isn’t yet fully understood. It wasn’t until we approached the middle of the twentieth century, with the first electronic monitoring of the brain, that we began to get a clearer idea of the nocturnal adventures of the mind. For centuries it was thought that the purpose of sleep was to rest the body and the mind, but this reasoning was disproved when it was shown that both the body and mind are active during sleep. If sleep doesn’t rest the body or mind, then what is it for?

Sleep researchers may not yet have discovered the exact reason for sleep or dreams but they have discovered some fascinating things. For example, it seems that when we are asleep our brains are a bit like computers that are offline. This means they are not idle but are filing and updating the day’s activities. They take stock of your body and release a growth hormone to repair damaged tissues and stimulate growth, while the immune system gets to work on attacking any viral or bacterial infections that may be present. Some experts believe the brain also jettisons trivial information during sleep to prevent it becoming overburdened with unimportant information, but this explanation is perhaps too simplistic, as no memory can be totally eradicated.

The advent of space travel gave scientists the opportunity to prove that resting the body was not the main function of sleep. What they found instead was that prolonged periods of isolation decreased the need for sleep. In other words, the fewer stimuli received from people or external contacts during the day, the less sleep was required. It seems we have a sleep control center at the base of our brain linked with activity during wakefulness. When that gets overloaded we get tired, but if there have not been enough stimuli from the outside world, the sleep mechanism isn’t triggered. It seems, therefore, that boredom and lack of stimuli may account for many cases of insomnia. (Paradoxically, overstimulation also produces insomnia.)