Each night, we spend about one and a half to two hours dreaming. We dream about once every 90 minutes of sleep. The time you spend in dreams becomes longer throughout the night, from about 10 minutes to around 45 minutes or slightly longer. But what happens when we sleep?
There are five stages of sleep: four stages of NREM (Non-REM) sleep, also called SWS (Slow-Wave Sleep), and one stage of REM (Rapid Eye Movement) sleep. The most vivid dreams, and therefore the ones we remember the most, occur during REM sleep (though we dream in other stages too). One sleep cycle is roughly 90 minutes long.
(NREM) The first stage is a transition state between wakefulness and sleep. This is the stage that hypnagogic imagery occurs in. It usually passes into stage 2 within a few minutes.
(NREM) During stage 2, the body gradually shuts down, and brain waves become larger.
(NREM) Stage 3 usually occurs 30 to 45 minutes after falling asleep the first time. Large, slow delta brain waves are generated.
(NREM) Stage 4 is often called “deep sleep” or “delta sleep”. The heart beats the slowest and there is the least brain activity. It is during this stage that sleepwalking usually occurs. After stage 4, the NREM stages reverse and move back to stage 2, and then into REM sleep.
(REM) During REM sleep, some parts of the brain are nearly as active as while awake. In this stage, your eyes flicker rapidly (hence the acronym Rapid Eye Movement). Your body is paralyzed, probably to prevent you from acting out your dreams.
After the REM state, you sometimes wake briefly. This is usually forgotten by the time you wake up in the morning. If you don’t wake up, you go to stage 2.
Controversial: Creating Bad Habits or Becoming a Control Freak
When lucid dreaming, you have the option to control the dream world in ways that are impossible in the waking world.
You can, for example, make objects appear or disappear, or make people act according to your will. Some people believe this may lead your subconscious to desire this kind of control in the waking world, where it’s highly inappropriate. Also, you might be tempted to apply dream-world solutions to waking life problems instead of actually facing them; for example, just willing bad things to go away or escaping or destroying them by superpowers. Again, this is probably more of a problem if you are not mentally stable at the outset of your dreaming process.