Before you can learn how to lucid dream, it helps to know how we dream. It often seems like we go to sleep, dream then wake up, yet in reality our sleep cycle moves us in and out of dreams on a regular basis.

Throughout the entire night, we spend a total of about one and a half to two hours dreaming. In the earlier part of the night dreams tend to last closer to 10 minutes but as the night progresses, our dreams tend to get longer lasting up to about 45 minutes or slightly longer.

Throughout the night, our sleep moves in a cycle that tends to move up and then down through the 5 stages of sleep. There are 4 stages of Non-REM sleep (NREM) (also called SWS or Slow Wave Sleep) and one stage of REM (Rapid Eye Movement) sleep. About 80% of our dreams occur during REM sleep and this is where the most vivid dreams occur. These vivid ones are the dreams we remember the most often. Each of the sleep cycles last about 90 minutes.

(NREM 1) The first stage is a transition state between wakefulness and sleep. This is the stage that hypnogogic imagery occurs in. People tend to experience a feeling of floating off, sometimes accompanied by vivid or psychedelic images. At this point the brain is in alpha. It usually passes into stage 2 within a few minutes.

NREM 2) During stage 2, the body gradually shuts down, and brain waves become longer in wavelength.

(NREM 3) Stage 3 usually occurs 20 to 45 minutes after falling asleep the first time. Large, slow delta brain waves begin to be generated.

(NREM 4) 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. The quite phase occurs during deep sleep and is known as "SWS" sleep, as it is characterized by slow wave EEG. This Delta pattern takes up most of our sleeping time, thus the "SWS". It is the state of restful inactivity, your mind does little while you breathe slowly and deeply; your metabolic rate is at a minimum, and growth hormones are released facilitating restorative processes. When awakened from this state, people feel disoriented and rarely remember dreaming.

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. This second type of sleep pattern, REM (rapid eye movement) is the sleep state that pertains to lucid dreaming. REM sleep or "D" sleep is characterized by rapid eye movements and is often accompanied by dreams, thus the D. The first episode of REM or D sleep in adults lasts about ten minutes but can increase to as much as an hour throughout the night. During REM sleep your eyes move around rapidly, breathing is quick and irregular, and you dream vividly. During this activity, your body remains still, because it is temporarily paralyzed during REM sleep to prevent you from acting out your dreams.

The length of REM periods increase as the night proceeds, and the intervals between REM periods decrease. The first REM period usually lasts about ten minutes, after which the sleeper almost awakens before stage two. The cycle is then highly variable with each individual. Usually the complete REM/non REM cycle lasts about 90 minutes, with the dreamer experiencing four to five cycles of sleep each night. During the last two hours of sleep the REM period tends to increased from ten minutes to as much as one hour.

Therefore "dreaming sleep" accounts for as much as 20 percent of our sleeping life. We spend as much as five years in dream worlds, and experience over 150,000 dreams in a lifetime. During the last several decades, sleep researchers have discovered that for every 100 persons in REM sleep, over 80 percent will remember a dream if awakened. REM is clearly a unique brain state, though it is similar to the waking state in EEG activity. This may explain why dreams seem so real. While other structures in the brain are involved in sleep, the neocortex is the major brain area involved in the production of dream images and experiences.