Is it beneficial or harmful to get more REM and Deep sleep than light sleep?

by Ryan@Zeo on June 10, 2011

Q: On a typical night (7-8hr sleep) I’m getting roughly 35% REM, 35% Deep, and 30% Light. Since light sleep (stage 2) is involved especially in memory consolidation do you think this is harmful? Are these numbers relatively abnormal?

A: An even balance of REM, Deep and Light sleep is most likely within the healthy range, provided you are getting enough sleep in total and feel rested throughout the day. Memory consolidation happens in all stages of sleep to a degree, so you’re covered.

Everyone has a unique blend of the time spent in each stage of sleep; it’s really a personal thing. The most important factor is how rested you feel after waking and during the day. If you find yourself catching up on sleep on the weekends, then it’s a good sign that your current sleeping schedule isn’t sustainable or truly adequate to your body’s needs.

As for learning, memory consolidation appears to happen during Light sleep and is associated with sleep spindles. Spindles in sleep may turn out to be a measure of intellectual ability, which is one of the best excuses I’ve ever heard to take an afternoon nap.

Light Sleep with Characteristic Sleep Spindles

However, consolidation also occurs in REM sleep and Deep sleep. Different sleep stages may be associated with different kinds of memory, the two main types being declarative and procedural memory.

Declarative memory, which is about facts and personal experiences, is stronger in the first half of the night when we are mostly in Deep and Light sleep stages.

Procedural memory, on the other hand, is about processes and skills—how to do things—and it appears to play a bigger role in the second half of the night, when we spend more time in REM mixed with Light sleep.

In addition, hormones may play a big role as well. Cortisol increases throughout the night which appears to help with the overall memory processes during sleep.

Finally, dreaming of a particular task may make a difference in future performance. This 2010 study found that subjects who dreamed of a maze had better recall compared to those who napped but did not recall a dream.

So while many non-sleep factors influence the memory formation process, each sleep stage does play an important role as brain transfers information from short term to long term memory.

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