Prior to the 1920’s, the prevailing belief in the mainstream scientific community was that sleep represented a time when brain function diminished. Largely due to an inability to record brain activity, modern sleep research essentially believed our brains turned off when we went to sleep.
By 1929, scientists developed electroencephalograms also known as an EEG. An EEG is a test that detects electrical activity in your brain using small, flat metal discs (electrodes) attached to your scalp.
From these recordings researchers learned that the brain was highly active at all times, including during sleep.
Stages of Sleep: REM & NREM
Inspired by this discovery, scientists developed other instruments to measure eye movements and muscle activity. These developments helped researchers define two main types of sleep: rapid-eye-movement (REM) sleep and non-rapid-eye-movement (NREM) sleep.
REM sleep is identifiable on an EEG by small, fast waves (see the diagram below). REM sleep is also accompanied by eye movements, which accounts for the name, as well as temporarily paralyzed muscles in the arms and legs. Typically, when one is awakened from REM sleep, they report having been dreaming. For this reason, researchers believe that these rapid eye movements are somehow related to dreams.
Stages of Sleep Chart
By contrast, NREM sleep is identified on an EEG by large, slow waves (see diagram above). What’s more, people awoken during NREM sleep report dreaming far less frequently than when awakened from REM sleep.
Which Stage of Sleep is Important?
A healthy adult typically experiences REM sleep about 20-25% throughout the night. Generally speaking, during NREM sleep the body repairs muscles and tissues, stimulates growth and development, boosts immune function and builds up energy for the next day.
REM sleep, on the other hand, plays an important role in learning and memory function, since this is when your brain consolidates and processes information from the day before so that it can be stored in your long-term memory.
Creating a sleep environment that allows for both beneficial REM and NREM sleep is important for healthy function. Luckily, studies show that people sleeping with wool bedding have a lower heart rate, less sleep disturbance and increased duration of beneficial sleep.
Learn more about the benefits of wool bedding.