Does anesthesia put you to sleep? A long review of what really happens in anesthesia, published recently in the New England Journal of Medicine, points out something cognitive scientists have known for a long time: Our layman's terms provide little explanation of how extraordinarily varied human consciousness actually is. Rather than experiencing just different levels of consciousness, we normally undergo many different states.
One is coma — unresponsiveness to outside stimuli, plus a brain that can't accomplish much beyond the amazingly complicated process of keeping you alive. It turns out that anesthesia is a lot closer to coma than some people thought. More bizarrely, sleeping pills like ambien (zolpidem) seem to produce states that ape parts of coma.
Here, with apologies to cognitive scientists and philosophers, is a consumer's guide to the more common states of consciousness you may encounter in your daily life.
1. Stage 1 sleep demonstrates that states of consciousness not only fluidly run into each other, but often are not recognized. Many people have microsleeps of 3-30 seconds, especially when driving late at night. Often they are not experienced as microsleeps, or even as blips of changed consciousness — with sometimes fatal results. Akerstedt's studies of Swedish train conductors showed that they routinely fell asleep at night, standing up, with their eyes open. (Fortunately for us, professional truck drivers appear pretty good at knowing when microsleeps are going to hit them.)
A Henry Ford Hospital study by Rosenthal et al. put people into stage 1 sleep for 10 minutes. When it was over, fully half thought they were awake the whole time. They were not. Some were snoring away. They just thought they were awake — and argued vigorously with the researchers, even when shown videotapes of what they did during those 10 minutes.
It may be better to see the brain the way Marvin Mirsky theorized long ago: as a bunch of "kludges," or engineering systems jerry-built to do one thing, like vision, that through evolution got involved in 15 or more activities of which they are necessary but insufficient parts. It's kind of like thinking of a plywood two-by-four as potentially part of a table, the base of a floor, a weapon, bed headboard, elevator, plane for writing, carved signboard, room divider, toy, plus who knows what else.
To get to stage 1 sleep you need dozens of different kludges to work seamlessly together. It's more like putting nine separate orchestras in different sections of the Houston Astrodome, some in the boxes, others on the field, a few players in the washrooms, and getting them to simultaneously play the same notes in the same rhythm. If that doesn't happen you might jerk up like students in high schools and universities do throughout the morning, or like commuters on train cars (hopefully not while reading this sentence).
2. Delirium. Fluctuating states of consciousness confuse the heck out of people but are very common. You often see it in elderly people, who will shift suddenly from talking about the stock market to forgetting your name or where they are. However, intoxication, often with alcohol or marijuana but progressively more commonly through prescription medications, can produce the same effect. New Year's Eve is one time when you can watch many different examples of mild delirium.
3. Early-morning wakefulness. Getting up is hard to do, as your cold brain tries to warm up and notice what's going on. This is essentially a state somewhere between stage 1 sleep and wakefulness, and can lapse in and out of the two for many minutes before people stop hitting the snooze button and actually rouse themselves out of bed. Getting out, moving, and seeking sunlight are great ways to start to get awake. However, full alertness may still be hours away.
4. REM sleep. Commonly thought of as dream sleep (although we actually can dream in any stage of sleep) REM is a bizarre state of consciousness. Temperature controls disappear, while the many kludges of the brain seem to communicate with each other in a sometimes forlorn attempt to take the new information of the previous day, anneal it with old memories, and remake it into newer information the body then uses to remake itself. A time of much rewiring and rejiggering of memory and thoughts, including peak testosterone production, the fragments of what REM produces as it helps remake the brain become what we call complex dreams.
5. Deep sleep. Often appearing in the first part of the night, deep sleep is as close to coma as we get. Also a time of massive rewiring, deep sleep is when growth hormone is pulsed out into the blood. In deep sleep, you literally grow, though you may not be able to be forcefully awakened for two or more minutes — thus the term deep sleep. Oddly, deep sleep is where sleepwalking and other funky sleep movements occur. Generally they are not remembered — because you're in deep sleep. These "confusional arousals" probably occur because the circuitry turning off physical movements fails.
It's Always Different
Consciousness is not just a bunch of different levels. It's a group of different states, of which the best worked out are those involving wakefulness and the different stages of sleep. But everything is fluid. Just as we move in and out of alertness, ranging from paralyzed semi-conscious television watching to our lives' creative peaks, what we remember and what we don't involves many different shifts of consciousness. Every day, from minute to minute and hour to hour, our consciousness moves through different levels of wakefulness and productivity. Like the differences between sleep and wake, it's no light switch.