Sleep is an essential part of life: every day, we dedicate approximately one-third of our lives to it. Throughout a typical night’s rest, our brains and bodies transition between two distinct states of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Both states are important to overall health and wellness, but they are unique in their purpose.
NREM sleep consists of four stages. During the first and second stages, people are in light sleep and relatively easy to wake up. During the third and fourth stages, people are in deep sleep and more difficult to wake up. Throughout NREM sleep, the body repairs muscles, consolidates memories, and regulates hormones.
REM sleep is very different from NREM sleep, as it is characterized by intense brain activity. During this stage of sleep, brain wave activity spikes and the eyes begin to move rapidly, hence the name. This stage of sleep is important for physical and mental restoration and plays a role in learning and memory.
NREM Sleep: Stages and Functions
NREM sleep is typically thought of as the “deep sleep” stage. It’s during this stage that the body enters its deepest states of relaxation, and the brain refreshes itself for the day ahead. It includes four distinct stages: Stage 1, Stage 2, Stage 3, and Stage 4.
Stage 1 is when your body begins to transition from wakefulness to sleep. You may experience sudden jerking movements, or hypnic jerks, during this stage. Stage 2 is when your body is in a light sleep state and your breathing and heart rate become more consistent. You will usually enter Stages 3 and 4 quickly, but together they will make up the majority of your sleep time.
Functions of NREM Sleep
During NREM sleep, the body repairs muscles and refuels energy stores. It also helps to regulate hormones and support the immune system. Additionally, it facilitates the consolidation of new memories and helps new information to become encoded into long-term memory. NREM sleep also supports physical growth, helping children and teenagers to reach their milestones.
NREM sleep, particularly during deeper stages, can help to reduce stress and improve emotional well-being. In particular, the slow-wave (delta) brain rhythms that emerge during NREM sleep help to dampen over-activity of the amygdala, allowing our brains to process emotions more effectively.
Finally, NREM sleep helps our brains to focus and concentrate. It is during this stage of sleep that essential nutrients are replenished and cells in the brain are restored, allowing us to focus and concentrate more effectively upon waking.
REM Sleep: Characteristics and Functions
REM sleep is the dream state. It takes up about 25-30 percent of total sleep time and is known for its enhanced brain activity including vivid dreams and rapid eye movements. During REM sleep, heart rate and respiration both increase as brain wave activity is at its highest level.
REM sleep helps to restore both physical and mental energy. It plays a role in regulating emotions and modulating them for optimal functioning. During REM sleep, subconscious thoughts are processed and integrated into long-term memory. It also help to foster creativity by priming the brain with new ideas and fostering connections between different and seemingly unrelated concepts.
Finally, REM sleep helps to recharge us for the day ahead. By helping us to process information and store memories, our brain is better equipped to handle the tasks that need to be completed during the day.
Benefits of NREM and REM Sleep
- NREM Sleep:
- Repairs muscles and replenishes energy stores
- Regulates hormones
- Helps to consolidate memories and store new information
- Supports physical growth in children and teenagers
- Reduces stress and improves emotional well-being
- Allows our brains to focus and concentrate
- REM Sleep:
- Increases brain wave activity
- Restores physical and mental energy
- Regulates emotions for optimal functioning
- Processes and integrates subconscious thoughts
- Fosters creativity
- Recharges our brains for the day ahead
Conclusion
NREM and REM sleep both play important roles in our daily lives. While these two states of sleep are distinct, they are both crucial for our overall health and well-being. By allowing our brains and bodies to enter different stages of relaxation and arousal, we can ensure that we are well-rested and ready to take on the tasks of the day.