Approximately one third of our life is spent asleep but when I started to think about sleep, I realised that my mind was completely blank. All i knew was that all creatures go to sleep at some point in 24 hours. To find out more, I went to spend a weekend with Dr Hernandez, director of the local Sleep Laboratory. I took a long list of questions to ask her.
First of all, I wanted to know why we sleep. Dr Hernandez said:
“Well. years ago we didn’t really know, but recent science has shown that people who don’t sleep enough soon get ill and often die.” So it seems that when we sleep our bodies are being “repaired”. She went on to say that a lot of natural chemical come to our blood while we sleep and these can help cure minor illness such as colds.
I wondered if our bodies experience any other changes while we sleep. Dr Hernandez replied:
“In some stages of sleep the heart rate and our breathing slow down but in other stages the opposite happens – the heart rate increases and our breathing becomes quite rapid. During the the night our body temperature drops by one or two degrees too.”
In the laboratory there were six volunteers fast asleep with wires attached to their heads. The wires were connected to a monitor. The monitor was measuring the brain’s electrical activity and showed which of the four stages of sleep the volunteers were in.
I wanted to know what happened in the differend stages. Dr Hernandez explained:
“After we have slept through the four stages – which takes about 40 minutes – we then go backwards through the stages again, four, three, two, one. Stage four is the deepest sleep. Each stage is deeper than the one before. Look now at the volunteer’s eyes. Those rapid eye movements (REM) are telling us that they are dreaming. If we wake them up now they’ll remember their dreams quite clearly.”
Then it was my turn to be a volunteer. I started to listen to some instructions and… yawn… yawn…
(Rita Slavin)
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