Though I’m thankfully way past my student days, I still experience recurring dreams about school. I have an important exam to get to, I can’t remember a word of what I read in the textbook the night before, and I’ve forgotten in what room the test is being held, as I run in panic through halls, desperately looking for someone I know going into a classroom to give me a clue.
Dreaming is a universal human experience; although there are a number of themes running through them, dreams are also unique to the dreamer, capable of provoking not only fear and anxiety, but also wonderment and calm. Animals appear to have them as well, though we are in the dark as to their content. Considering that we spend roughly a third of our lives sleeping and dreaming, it seems remarkable how little we actually know about our need for this proven vital activity.
If you are interested in the science of sleep and dreaming, you might enjoy reading “When Brains Dream” by Antonio Zadra and Robert Stickgold, leading researchers in this topic, as recently reviewed in the WSJ. They note that “for it to have been maintained across half a billion years of evolution, sleep must serve functions critical to our survival.” When I was in medical school and interested in this topic, we learned that one of these functions is cellular housekeeping. More recent science has shown that sleep deprivation leads to impaired insulin signaling. In one study of otherwise healthy college students, limiting their sleep to only four hours a night made them look and act prediabetic. During my studies, I also learned that during sleep, unwanted waste products were cleared from the brain, one of which was recently shown to be beta-amyloid, the prime suspect in Alzheimer’s disease.
Attempts to understand and interpret dreams are woven throughout our history. Dreams and their meanings play prominent roles in religious traditions from Buddhism to Judaeo-Christian writings, from Greek philosophy to Freud and Jung. Some have looked on dreams as prophecies coming from God or Spirits, while others have felt that they exist to encode our memories of the prior day. The writers of this book offer evidence that the process is significantly more complex, that we actually dream in all four stages of sleep, not just REM sleep (as previously thought), and that the four sleep stages have different functions. They hypothesize that the neurochemistry for strengthening one kind of memory, say playing an instrument, is different from emotional memories and abstract problem solving, the latter of which they place during REM sleep. They feel that this is the best explanation as to why we have so many different stages of sleep.
When we are awake, the brain is a problem solving machine, receiving broad bandwidth input through all our five senses, and functions primarily in a linear fashion. During sleep however, the brain is able to process earlier input, and search through its database of weaker stimuli, searching for possible close matches to recent experience, and strengthening inputs in a non-linear fashion, thus creating new ideas and concepts. Clearly, our ignorance regarding sleep and its associated dreams remains vast. Yet the ideas and the evidence presented here are intriguing. Certainly, something to dream about.