Understanding Sleep Cycles and Why They Matter. What Happens During REM Sleep?

Professor Goodsleep
Jun 16
2 min read

Updated: Jul 3

The Importance of REM and Deep Sleep Cycles

Most people know they need sleep, but not all sleep is created equal. You can spend eight hours in bed and still wake up exhausted if your sleep cycles are constantly interrupted.

To understand why, we need to look at one of the most important parts of sleep: REM sleep.

What Is REM Sleep?

REM stands for Rapid Eye Movement. This stage of sleep is associated with dreaming, memory formation, learning, emotional processing, creativity, and mental recovery.

Sleep Happens in Cycles

A typical sleep cycle lasts approximately 90 to 120 minutes and includes light sleep, deep sleep, and REM sleep. Most healthy adults complete 4 to 6 sleep cycles every night.

Deep Sleep vs REM Sleep

Deep sleep focuses on physical recovery, tissue repair, immune function, and muscle recovery. REM sleep focuses on mental recovery, learning, memory, and emotional processing.

Why the Last Few Hours Matter

REM periods become longer as the night progresses. Many of your longest and most important REM periods occur during the final few hours before you wake up.

My Personal Experience

Before I got into the sleep industry, I had a mattress that gradually wore out. I eventually found myself waking up six to eight times every night.

Every time I woke up to reposition myself, I interrupted my sleep cycles. I was spending enough hours in bed, but I wasn't getting the uninterrupted sleep my body needed.

How Much REM Sleep Do You Need?

Most adults spend approximately 20% to 25% of their total sleep time in REM sleep. For someone sleeping eight hours, that works out to roughly 90 to 120 minutes of REM sleep spread across multiple sleep cycles.

Signs You May Not Be Getting Enough REM Sleep

Common signs include brain fog, poor concentration, memory issues, irritability, waking up tired, and frequent nighttime awakenings.

How to Improve REM Sleep

Maintain a consistent sleep schedule, allow enough time for sleep, reduce caffeine late in the day, address snoring or sleep apnea, and make sure your mattress and pillow support proper alignment.