Sleep, Dreams, and Consciousness

SLEEP, DREAMS, AND CONSCIOUSNESS

What can we learn about consciousness by studying sleep and dreams? At the very least, sleep provides a compelling reminder that our conscious state varies—it has different degrees of alertness as a function of our own internal status. Sleep also reminds us that consciousness is intermittent; for some portions of the day, we aren’t conscious. This seems to be true during sleep, but it’s also true when we’re awake. (Consider the relatively common experience of suddenly realizing, after 30 miles of highway driving, that you haven’t been aware of the passing miles at all. You were driving on autopilot—steering, maintaining your speed, and so on; but you had “zoned out” and have no recollection of the last half hour.)

Sleep and dreaming also remind us of the sheer difficulty of studying conscious experience. Notice, for example, that we have plausible conjectures about why we sleep; but there’s no widespread agreement. Likewise, the activation-synthesis notion strikes many researchers as a promising account of why we dream, but the debate continues about whether this proposal is correct. And we still have many unanswered questions about why people’s dreams have the contents they do—and why so many people have dreams of flying (for example), appearing naked in public, or being chased.

Why is this research so difficult? It’s partly because the study of sleep and dreaming often must depend on what people recall and report about their sleep and their dreams. Self-report data are always worrisome, but the problem is magnified when the self-report is offered by a groggy, disoriented, just-awakened sleeper. What’s more, we have powerful reason to be skeptical about this particular self-report because—as mentioned earlier—we know that some people assert they never dream, but these same people reliably report dreams if we manage to awaken them during an interval of REM sleep. In this case, their self-report of never dreaming is patently incorrect, highlight-ing for us the challenge of relying on people’s descriptions of, and their memories of, their mental states in general and their nighttime states in particular.