For most people the prospect of a warm comfortable bed to sleep in is a relief after a long hard day of work or school or activities.
“Sleep” by Salvador Dali (1931)
For others, sleep is simply another hardship to cap off a tough day. There could be lots of reasons to feel apprehensive about sleeping — perhaps one has trouble falling asleep, or perhaps one is concerned about having nightmares. Or maybe it’s just a fear of the darkness.
Today I want to talk a bit about dreams. However, I don’t really want to get in to where our dreams come from. I know there are a lot of theories and suggestions and perhaps another time I’ll dive into that mystery, but for today I want to talk about some of the physiological effects that occur to us when we dream.
Why on earth would I want to talk about that? How is that related to skepticism? Because dreams can have a powerful effect on our beliefs, our thoughts, and our experiences.
Have you ever awakened with the feeling you are not alone? Have you ever had the sensation you were floating above your body? What about someone calling you or a strange sound or voice coming from the darkness? Or, most terrifyingly, have you ever awakened unable to move only to see something hovering or sitting right on top of you?
If so, you’re not crazy. But it might just be in your head.
First, let’s look at why we sleep. For some, it’s a pleasant experience, but there are more biological reasons for sleeping. Sleep allows our bodies to recover from the day’s activities, process waste products, repair cells, and maintain the immune system.
Back in the 1950′s physiologist Nathaniel Kleitman discovered that there might be more to sleep than meets the eye (pun intended). Along with his research assistant Eugene Aserinsky, they were the first to discover and document Rapid Eye Movement or REM sleep. They realized that while you sleep your eyes make rapid little movements side to side ans they were able to correlate these movements to changes in brain wave patterns, muscle tension, breathing, and other physiological responses.
During sleep, we go through a series of stages where eye movements alternate between periods of rapid or slow in an ultradian cycle:
- The first stage is characterized with small, irregular brain waves. During this stage you might be just falling asleep.
- The second stage is characterized with short emissions of rapid, high-peaking waves called sleep spindles.
- In stage three your brain starts to emit delta waves, very slow waves with very high peaks, at this point your biological functions have slowed down and you would be hard to wake.
- In stage four delta waves have become the norm and you are very difficult to wake. However, it is in this stage that you are most likely to sleep walk or talk while sleeping.
This whole sequence takes about 30 to 45 minutes, then you move back through the stages from 4 to 1 again. After completing stage 1 for the second time, you enter REM sleep. Once in REM sleep (your eyes are moving rapidly beneath your eye lids) many biological changes occur, your heart rate rises, as does your blood pressure. Your breathing becomes faster and irregular, your muscles twitch and your sexual organs may become aroused. However your muscles also become limp and you won’t be able to move. (This way you won’t get up and act out your dreams)
The impression I’m trying to give is that your brain isn’t passive while you sleep. It’s very active. A lot of complex things are happening to your body and that should give you a clue to why strange things might be perceived when you unexpectedly wake up.
Sleep disorders also come into play. Parasomnia for instance occurs in NREM sleep (stages 1 through 4) you might experience something like sleep walking, night terrors (they sound worse than they are), or a confusional arousal (which could be a series of strange movements or even fits of crying – common in children)
If you wake up suddenly and unexpectedly in REM sleep you might experience sleep paralysis. The name really explains it. You are unable to move or speak. It is often associated with a feeling that you are not alone, bringing about intense fear. This is only made worse by the feeling of not be able to move or cry out. Because you’ve just woken up from sleep, and REM sleep usually involves vivid dreams, you may also experience visual or auditory hallucinations.
Sleep paralysis has long been suspected of being the rational explanation for alien abductions, ghost sightings, spiritual visitations, or other paranormal events. Chris Mooney summarized it nicely in a 2005 article in Skeptical Inquirer.
It’s not surprising that sudden insomnia, somnambulism, or parasomnia could be perceived as something fantastical like an alien visitation given how active our brains are when we sleep. In my personal experience when someone has told me about a ghost sighting that occurred at night, their experience could generally be explained as a result of a sleep-related incident. Usually this is taken as a direct attack on their intelligence — they obviously know what’s a dream and what isn’t.
I can attest that these events are very realistic. I’ve experienced sleep paralysis and it can be a terrifying experience. But getting back to knowing your dreams, how often are you able to recognize while you dream that you are dreaming? In your dreams, when you encounter something like a talking can of tuna, how often do you say “wait a minute! This is just silly!” I’d wager it’s not very often. That’s because the rational centre of your brain shuts down while you dream. So in theory you could dream something about aliens (in your dream believing it’s perfectly rational) only to wake up with sleep paralysis unable to move or scream while it feels like someone is watching you.
The Nightmare by John Henry Fuseli (1781)
The really interesting thing to me is how influential our dreams can be. There are many theories suggesting that a combination of dreams, sleep disorders, and sleep paralysis are the origins for a wide variety of demons, ghosts, monsters, vampires, and other paranormal believes in human civilization. For example, the notion of waking to find a demon sitting on your chest (related to difficulty breathing, perhaps sleep apnea?) seems to be quite common in medieval folklore.
Even the notion of succubi and inccubi, demons that seduce you in your dreams and feed off your sexual energy, could be related to physiological effects that occur to your body while you sleep. The really interesting thing is, when people experience sleep paralysis nowadays, they don’t usually attribute it to a horny demon or little goblins that sit on your chest. Often it’s attributed to aliens or ghosts. Why would that be?
An explanation might be that each culture just finds a new boogieman to slot into the irrational explanation for sleep paralysis. So in the medieval days it was demons and succubi. Currently it’s aliens and ghosts. The interesting thing is how the cultural meme that is terrorizing us while we dream still operates within the symptoms of sleep disorders when reported later. So if it’s sleep apnea (difficulty breathing during sleep) the hallucination is some kind of smothering entity. If it’s sleep paralysis, the hallucination accounts for the paralysis. And if it’s a succubus…well, you get the picture.