<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=1717549828521399&amp;ev=PageView&amp;noscript=1">

«  View All Posts

Blog Feature

By: Brendan Duffy, CCSH, RPSGT on August 9th, 2018

Print/Save as PDF

Sleep Spindles and Memory

sleep technologist | school start times | "Memory"

Recently, I have been reading the book “Why We Sleep” by Matthew Walker, Ph.D. He not only has a passion for all things sleep, but he has a superb knack for explaining the subject matter in a very friendly and easy-to-understand manner. This is a gift for a writer of science when one is trying to reach a large audience and improve health issues by explaining such sleep topics as “synaptogenesis,” which he whittles down to a definition of “the creation of millions of wiring links, or synapses between neurons” and “an overenthusiastic first pass at setting up the mainframe of a brain” of an infant.

Another area that intrigues Walker is the relationship between sleep spindles and memory. The research is fascinating in this area, and Walker and his research staff at the University of Berkeley have brought forth findings that suggest that sleep spindles may be the transport mechanism that moves our memories from a temporary storage area, the hippocampus, to a more permanent storage “hard drive” area in the prefrontal cortex of the brain.

Sleep technologists are very familiar with sleep spindles, as we see them nightly in stage N2 sleep along with their stage N2 partner, the K complex. Sleep spindles are also referred to as sigma waves or sigma bands. These fast bursts of EEG activity are usually between 12 and 14 Hertz and are believed to be an information processing and transferring feature of the sleeping brain.

In addition to memory transfer, Walker describes one of the sleep spindles functions as “the nocturnal soldiers who protect sleep by shielding the brain from external noises.” He goes on to say that spindles “appear to predict learning refreshment.”

Walker’s team at Berkeley did a study that was published in 2011 that indicates that the second half of the night is where most of the stage N2 “spindle rich” sleep occurred and that if you sleep six hours or less you may not reap the learning benefits of this memory enhancer. This begs the question as to what cost will we bear for early school start times if we are not allowing teens to fully experience these spindle-induced memory transfer and storage segments of sleep.

Walker concludes, in an online article in MedicalXpress.com in 2011, that “Our findings demonstrate that sleep may selectively seek out and operate on our memory systems to restore their critical functions.” He also describes this in his book as “sleep-futureproofing our memories.” It appears a big player in that memory process is that busy burst of brain waves that we, as sleep technologists, know as the sleep spindle!


  1. Walker, M. (2017). Why We Sleep. Scribner; NY, NY.
  2. Anway, Y. (March 8, 2011). As we sleep, speedy brain waves boost our ability to learn (w/ Video). University of California - Berkeley https://medicalxpress.com/news/2011-03-speedy-brain-boost-ability.html