REM Sleep
Category: Sleep Science
Dreaming While the Brain Stays Alert
REM sleep (rapid eye movement sleep) is the sleep stage in which the eyes move quickly beneath closed lids. Brain waves take on an active pattern close to that of waking, while the skeletal muscles stay almost entirely slack, producing the peculiar condition of a body asleep with a brain awake. In 1953 Aserinsky and Kleitman confirmed that these eye movements lined up with reports of dreaming, and the scientific study of dreams started from there. REM sleep accounts for roughly 20 to 25 percent of a night, and each REM period runs longer in the later cycles, so the closer to morning you wake, the likelier you are to carry off a long dream with a thread running through it. That uneven distribution is why the dreams from early in the night are almost impossible to recall while the one just before waking stays sharp.
The Key Difference from Non-REM Sleep
REM sleep and Non-REM sleep alternate through the night, but the dreams that come out of them differ in texture. A dream in REM sleep tends to have a storyline and to arrive with color and emotion, like watching a film, whereas a dream in Non-REM sleep more often stays fragmentary and abstract. When someone brings a dream to a reading and says they had it last night, it is safe to assume most of those dreams came out of REM sleep. Still, the belief that you don't dream during Non-REM sleep is a common misconception: dreams do occur there, they just don't stick in memory. For whoever is reading the dream, the difference shows up as a difference in the material. A dream with a before and an after, where you can follow what the figures did, can be worked through scene by scene. A fragment that leaves only a color, a sound, or a texture is better written down for the feeling it left behind than forced into a plot.
A Key to More Accurate Dream Divination
Any interpretation worth the name depends on remembering the details of the dream. Waking naturally at the end of a REM period leaves the dream vivid, so it is worth some effort to line up the moment you get up with your sleep cycle. The advice you see most often, setting the alarm at a multiple of 90 minutes after you fall asleep (six hours, seven and a half hours), does not transfer to your own nights as neatly as it sounds. The length of a single sleep cycle varies from person to person and stretches or shrinks across one night in the same person, so 90 minutes is a starting point rather than a rule. Shift your wake time in small steps over several days and note which times left you holding a dream; the hour you found by testing will be a firmer guide than the number. Keep a dream journal at the bedside, write the moment you open your eyes, and the amount of usable material rises sharply. Memory fades fast once you sit up, check a clock, or speak to someone, so the practical move is to stay in the same position and write the scenes down in whatever order they come back.
Common Misconceptions
REM sleep is often dismissed as shallow sleep and therefore poor sleep, which isn't accurate. It is understood as the stage involved in consolidating memory and processing emotion, and one view holds that a shortage of it leads to weaker concentration and an unsteady mood. Rather than ranking rest by depth, it is closer to the truth to see Non-REM sleep and REM sleep taking turns at different jobs. Alcohol also suppresses REM sleep, so in the first half of a night after drinking you dream less and there is less material to read. Once the alcohol has been metabolized, the REM that was held back returns in the second half, and that rebound is how waking easily toward dawn, or remembering nothing but restless dreams, tends to be explained. The sense that a drink helps you sleep comes from how fast you drop off; it says nothing about whether the night as a whole held together. While you are gathering dreams to work with, records from nights without alcohol make the better baseline.
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