Science is only just starting to understand the deepest stage of our sleep. Make sure you don’t sleep on what we do know.

REM sleep gets its name from the rapid eye movement we experience in the deepest stage of our sleep. However, a lot more is happening behind our eyelids. Read on for five phenomena that rouse while we rest.

1. Eyes move as if looking at things

Man in a deep sleep

REM occurs around 90 minutes into our sleep. Our eye movements aren’t random, in fact, they replicate the way we take in our surroundings while awake. Our REM gaze suggests we’re scanning a dream scene and, interestingly, those born without sight also experience scanning eye movements. Although congenitally blind people’s dreams aren’t visual, their brains are activated in a way that mimics visual stimulation.

2. Limbs become immobilised

Young child in deep sleep

During REM, the muscles in your legs, arms and fingers switch off, preventing the body from acting out our dreams. Waking up to experience this sleep paralysis effect, is the basis for incubus myths, demons who are said to pin people down to their beds. Evidence suggests that those with REM sleep behaviour disorder (RBD) are more likely to develop a neurological condition later in life.

3. Dreams are at their most vivid

There’s a common misconception that all our dreaming occurs during REM sleep. Most of our dreams come at this time, but we also experience dreams in the other stages of our sleep. The dreams experienced during REM tend to be more vivid and around 80% of adults will remember at least part of their dream if they are woken from REM sleep. The unique alertness of the sleeping stage can lead to lucid dreaming, when you become aware that you’re dreaming and take control of events.

4. Your brain is working overtime

REM sleep is known as ‘paradoxical sleep’ in recognition of the high level of brain activity you experience while resting. Although you’re at your most difficult to wake up, your cognitive function resembles that of somebody awake, more than someone in other sleep stages. Paradoxical sleep is essential for the development of the brain and new-borns spend 80% of their sleeping time in this stage. Adults however, only experience REM for 20% of their sleep.

5. Your memory and problem-solving skills are boosted

Many dreams feel like your brain sorting out the loose ends of the day, this happens during REM and sleep experts refer to the phenomenon as memory consolidation. By doing this your mind can take on new memories, so a lack of REM may cause toxic proteins to build up and negatively impact long-term memory. During paradoxical sleep our brain makes connections with unrelated ideas that we might not make while awake. The kind of thinking that improves creativity and problem-solving.