Book: Functional Anatomy of the Sleep-Wakefulness Cycle – Review

Functional Anatomy of the Sleep-Wakefulness Cycle

This book is mainly about the specific nerves, hormones and other body parts responsible for sleep. Of course I should have known from the title, which has ‘anatomy’ in it, but this particular book was not too helpful for me. In a big part due to the fact I could not really read about the various experiments without gagging. But I concentrated and read through at least one particularly creative experiment.

The Sleep-Wakefulness-Cycle (SWC) simplified, exists of three stages: wake, non-REM sleep, REM sleep. Rapid Eye Movement (REM) sleep, is when you dream. Apparently, the cycle becomes longer in time, later in the night, which could explain why most people remember more complex dreams in the morning compared with when they wake up in the middle of the night. Also REM sleep is diminished in older people.

An experiment is described to see whether input on the body, influences the SWC. Normally, darkness causes certain hormones to be released which is why people and many animals sleep at night and are awake at day. The brain gives the command to release the hormones. But does the animal ‘know’ that its night, through his body or brain?

The conclusion was, that influences on the spinal cord nerves, must be responsible for the circadian rhythm. In other words, our brain does not dictate when we sleep, our body does!

***tender-hearted readers best stop reading now***

To come to this conclusion, the researchers separated one dog’s head from its body, but kept it alive by connecting the important blood vessels to a donor dog. So, now they have 1 whole dog (donor dog) and one connected head (isolated head).

The researchers then measured sleep activity in both heads. In the donor dog, the SWC was like a normal dog: short intervals of sleep during the day and more solid sleep during the night, meaning a day-night rhythm. In the isolated head, the SWC was continuous, in identical blocks, through the entire 24 hours.

Other experiments included making lesions (cuts) in the brain stem nerves of cats, to shut down different parts of their brain, and see what the effects of each was on SWCs.

I did find the theory very interesting but could not bring myself to read more. I think I will stick to psychological research from now on.

For more literature on sleep, see this post.

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