Sleep is a wonderland of mystery. Why do we need so much of it? Why do we dream? How am I still awake after lying in bed for 6 hours praying for the sweet release of unconsciousness? These are just a few of the questions that Penelope A. Lewis has studied as director of the Sleep and Memory Lab at the University of Manchester, and in The Secret World of Sleep, Lewis expertly leads an entertaining and informative scientific exploration of those many hours we spend twitching and drooling in bed.
We’ve all been victims of the memory lapses, irritability and slowed thinking that comes from lack of sleep, and Lewis pulls on a variety of scientific research to offer explanations on how this happens. A study with rats (aka the brave frontiersman who have performed much of the pathfinding in sleep studies), for example, shows that when they enter a specific sleep stage known as slow wave sleep, their little rat minds replay maze attempts and the number of times they replay these attempts can predict how well they perform on future maze tests. Buzzing rats with small doses of electricity to prevent them from doing these sleep replays, however, will cancel the improvements. In other words, sleep is important for consolidating memories and improving our ability to learn.
Lewis references dozens of studies to look at sleep from a variety of fascinating angles. Naps as short as six minutes, for example, have been shown to help us learn skills such as riding a bike, as well retain memories of what we ate for breakfast. Another study revealed that four years after reading a story about child murder, people who were allowed to sleep soon after reading the story were better able to access their emotionally charged memories than people who stayed awake after reading it.
Our memories, moods, and even our creativity are linked to our ability to sleep, but there are few conclusive explanations for why these relationships work the way they do. This isn’t Lewis’s fault. As she explains, the technology doesn’t exist (at least, the kind that won’t risk brain damage to people) that will allow us to examine our gray matter thoroughly enough to understand sleep processes. So we’re stuck trying to piece together how different studies can reach seemingly contradictory conclusions. For example, some studies show that sleep can strengthen our recall of emotionally charged experiences—making a terrible car crash live on in our memories—while other studies reveal that sleep could strip memories of their emotional impact and potentially be used to treat PTSD.
There’s a good reason why Lewis called her book The Secret World of Sleep, and exploring its mysteries is great fun for anyone who has even a passing interest into what goes on when our eyes are closed. There are a couple of chapters that go into the chemicals and neurotransmitters that make our brain work, but Lewis provides helpful summaries at the end of the more challenging chapters, as well as handy illustrations to smooth out the complexities. And as a special treat, Lewis even includes a chapter on ways to make your sleep more restful and productive. It isn’t a long book, but it’s loaded with information that will have you reconsidering your entire sleep routine.
Now if you’ll excuse me, I’ve got a nap to take.
The Secret World of Sleep is available now from Palgrave Macmillan.