How important is Light Sleep?

With all the emphasis on Deep and REM sleep, it can be easy to forget about Light sleep. However, Light sleep may be just as important to our ability to be at our best during the day.

In a typical sleep study, Non-REM sleep is comprised of several stages: Stage 1, Stage 2, and Stage 3.  On Zeo, Stages 1 and 2 are what we call “Light Sleep” while Stage 3 is “Deep Sleep”.  Stage 1 is often quite short whereas Stage 2 makes up about half a night of sleep.

Moreover, Stage 2 is where much of the action happens. Sleep spindles, a feature of Light sleep have been associated with synaptic plasticity, memory consolidation, improvements in declarative memory formation, and sleep spindle density has even been correlated with IQ.

In addition, the continuum between Light sleep and Deep sleep is very fluid; they are much more similar to each other than they are to either REM sleep or Wakefulness. In fact, it is possible to get a “deeper” Light sleep that is very similar to Deep sleep, and may even have the same effects as Deep sleep. This is especially true in older adults, who still have deeper Light sleep, but according to the gold standard for measuring sleep, aren’t getting much Deep sleep.

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