Circadian Health Glossary

REM and Non-REM Sleep

Getting a proper night's rest is vital for maintaining physical and psychological well-being. However, sleep comprises different phases. During the night, our bodies alternate between two primary stages of sleep: Non-Rapid Eye Movement (NREM) and Rapid Eye Movement (REM) sleep. Both phases are fundamental in ensuring we remain in optimal health and perform effectively.

What Happens During Non-REM Sleep?

Non-REM sleep, also known as quiet sleep, consists of three stages.

First Stage: We enter NREM 1, a shallow sleep phase with slowing brain activity and muscle relaxation, from which awakening is easy.

Second Stage: During NREM 2, we experience further slowed brain waves and muscle relaxation, alongside decreased body temperature and heart rate, making up a major part of our sleep.

Third Stage: The final phase, NREM 3, marks the deepest sleep, characterized by very slow brain waves and significant muscle relaxation. This stage is vital for physical recovery and immune system strengthening.

What Is REM Sleep?

REM sleep is distinguished by the quick movements of the eyes behind closed lids and is an essential phase of sleep. In this stage, although the brain becomes as active as it is during wakefulness, the body is immobilized to stop us from physically responding to our dreams. This stage is generally when the most vivid dreams occur. It’s believed that REM sleep is crucial for solidifying memories, processing emotions, and facilitating learning.

Stages of Sleep

During the night, our sleep alternates between NREM and REM phases. Initially, we start with NREM 1, moving through NREM 2 and 3 in sequence. Following NREM 3, we encounter our initial REM period, which tends to be brief. As the night continues, these cycles recur, with each REM phase extending in duration.
Related Definitions

Related Definitions

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