When do dreams occur when we’re sleeping? When we first dose off? When we meet Mr. Slumber? And why?
First, let’s look at the phases of sleep. Some consider there to be five stages of sleep, others to be four. The only area of disagreement basically is that the fivers believe the first 10 minutes of falling asleep comprise a phase. After that, each phase (all agree) lasts 90 to 120 minutes.
These sleep cycles repeat themselves four or five times each night, and you can dream in all of them but maybe not remember the dreams in the first three types of phases. The crucial point, however, is that those who get the “worst” sleep generally don’t get enough of what’s called REM (rapid eye movement sleep), but more of that in a minute.
The first stage (for the fourers) is falling asleep, which is called NREM, or non-rapid-eye-movement sleep. This is the lightest mode of sleep, when your body cools down and relaxes, as your heart beat also begins to slow. (The fivers say NREM follows first falling asleep.)
The second phase is just an acceleration of NREM with more relaxation of all parts of the body, including the heartbeat. This is considered a deep sleep, but still not the deepest.
The third phase features further acceleration of relaxation, and your metabolic rate becomes extremely low. It is a deeper sleep but still not the deepest.
The fourth phase (or fifth for the fivers) is now REM sleep, the deepest possible.This is also called delta sleep, and it is characterized not only by rapid eye movement but also by a rise in both blood pressure and heart rate. Your respiration becomes erratic and your brain activity increases (no doubt accounting for the more vivid dreams). In addition, your involuntary muscles become immobilized, almost paralyzed.
If you are awakened during REM — and often your dreams, now so vivid and involving, will awaken you by themselves — you will remember what you dreamed.
The first three cycles repeat themselves, but get shorter each time, leading back to dream-filled REM more quickly.
So what do dreams mean? We’ll perhaps look at that on another occasion, but for now, please realize that if you’re having trouble sleeping, you’re probably not getting enough of the REM deep sleep, and you should seek help if it’s more than a temporary occurrence.