The Amazing Things That Happen While You Sleep

Ever wonder what happens in your brain while you sleep? Or when dreams are most prevalent? Sleep is one of our most amazing biological functions. The sleep-wake cycle, also known as the circadian rhythm, affects every system in your body.

In the past, sleep was considered a passive state. A state in which the brain and body turn off to recover from stress and daily activities. Modern research shows that the brain is active during sleep, and goes through several cycles.  These cycles last approximately 90 minutes.  Within each sleep cycle we move through four stages of sleep.

The stages of Sleep

There two main types of sleep: NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement.) Both types have a direct impact on your energy levels and health.  REM is the phase of interest to the dreamer since this is the phase when the majority of dreams occur.

Let’s take a closer look at the stages of sleep.

  • NREM Stage 1  (N1) – Light sleep. Muscle activity slows. You may roll your eyes or open your eyelids. Brainwaves are transitioning from Alpha to Theta. Hypnagogia, which are mini “dreamlets” of visual and auditory hallucinations, happen in this stage. Accounts for approximately 5% of sleep.
  • NREM Stage 2 (N2)  – Breathing and heart rate slows. Theta brainwave activity. Decrease in body temperature. Approximately 50% of sleep.
  • NREM Stage 3 (N3) – Deep sleep begins. Slow Delta brainwaves. Also known as Delta sleep or slow-wave sleep (SWS.) Behaviors such as bed wetting, sleep walking, sleep talking and night terrors occur in this stage. Approx. 20-25% of sleep.
  • REM – Rapid Eye Movement. Brainwaves speed up. Breathing and heart rate are irregular. The muscles become paralyzed, a state called REM atonia. This paralysis keeps us from acting out our dreams. Most dreams occur in this stage.  Also known as “paradoxical sleep” since the brainwaves look like when you are awake. Approx 20-25% of sleep.

Sleep Cycles

These stages of sleep progress in a cycle from N1 to REM sleep, and then repeat until you wake up. The sequence generally goes n1 > n2 > n3 > N2 > n1 > REM and then repeats. An entire cycle lasts roughly 90 minutes. Most adults spend about 50 percent of their total sleep time in N2, 30 percent in other three stages, and 20 percent in REM sleep. Babies and children spend more time in delta sleep than adults do. If you wake up tired, you may not be spending enough time in REM and deep sleep.

Based on the cycle above, you will reach REM approximately every 90 minutes. REM stage duration increases with each cycle.  As you enter REM, your body temperature, respiration, and heart rate become irregular. During this stage, you may experience vivid dreams. Not getting enough REM sleep can affect your learning ability and mental focus. Babies spend up to nine hours a day in this stage. Understanding these sleep cycles and the stages within them will help your lucid dreaming practice.


You’re highly unlikely to have any lucid dreams as soon as your head hits the pillow at night. (Although you may enter REM sooner during an afternoon nap if you’re tired.)

Instead, your longest and most memorable lucid dreams will occur toward the end of the fourth and fifth sleep cycles of the night, after around six hours of sleep.”

If you have the luxury of sleeping-in most days, you’ll find you often wake up during or just after a dream has ended. This is the natural finish of a complete sleep cycle. With the dream fresh in mind, it’s much easier to remember. You’ll probably have lots of dreams to report.

-Excerpt from Rebecca Turner ‘s Lucid Dreaming Fast Track

Many things affect sleep including sleep environment, stress, diet, physical activity, medication, etc. REM sleep is more common in the later half of sleep and the duration of this stage is longer. Good information to know for your dreaming practice.

Focus should also be on getting enough sleep each night. Otherwise, you may wake up too early and miss out on that final REM stage of sleep.