November 23, 2017

Sleep and its impact on memory and learning

There were two interesting studies published this past week on sleep and its effects on memory and learning this past week. Sleep disturbance is a common problem in our everyday lifestyle and it has significant consequences on overall health, wellbeing, and brain function.

How we feel when we wake up has a lot to do with what happens while we were sleeping. Sleep helps our brain function properly, improves learning, and protects our mental and physical health. Lack of sleep also contributes to weight gain, how our body reacts to insulin, our immune response, and hormone dysfunction.

In the first study, researchers from the Netherlands and Pennsylvania have discovered a component of how the lack of sleep negatively impacts memory.

This animal study published in eLife demonstrated that five hours of sleep deprivation leads to a loss of connectivity between neurons in the hippocampus. This specific region of the brain is associated with learning and memory.

We all know adequate sleep is essential for overall health and sleep issues will exacerbate all chronic disorders. Previous research demonstrate the role of sleep and memory but this study shows that it impairs hippocampal function. The results indicate sleep deprivation significantly reduces the length and density of the dendrites of the neurons in the hippocampus.
They then repeated this sleep-loss experiment but left the mice to sleep undisturbed for 3 hours afterwards. This period is sufficient to restore deficits caused by lack of sleep. The effects of the 5 hour sleep deprivation in the mice were reversed. This demonstrates the importance of the nervous system’s ability to adapt to sleep loss and that these neuronal connections can be restored with several hours of recovery sleep. During this time these individuals are remodeling their brain.

A second study published in Psychological Science revealed how naps in between study sessions may make it easier to recall what you studied and relearn what you’ve forgotten even 6 months later. The improved memory from sleeping between sessions seemed to last over time. Follow-up data showed the sleep group outperformed their peers on the recall test 1 week later and this benefit was still noticeable 6 months later.

These results suggest that alternating study sessions with sleep might be an easy and effective way to remember information over longer periods of time.

Addressing sleep disturbances can very challenging with patients in practice. One product does not work for everyone. We all have our own biochemical individuality and there can be different underlying causes to an individual’s sleep issue. A patient can have a nutrient deficiency or hormone dysfunction. One person may have trouble falling asleep whereas another can’t stay asleep. Also, one botanical may have the opposite effect and stimulate a patient or another product may cause drowsiness. We also need to keep in mind, if we are recommending a product for a child or during pregnancy, we may want to avoid certain botanicals, neurotransmitters, and hormones.

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Robbert Havekes, Alan J Park, Jennifer C Tudor, Vincent G Luczak, Rolf T Hansen, Sarah L Ferri, Vibeke M Bruinenberg, Shane G Poplawski, Jonathan P Day, Sara J Aton, Kasia Radwańska, Peter Meerlo, Miles D Houslay, George S Baillie, Ted Abel. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1. eLife, 2016; 5 DOI: 10.7554/eLife.13424

Source: S. Mazza, E. Gerbier, M.-P. Gustin, Z. Kasikci, O. Koenig, T. C. Toppino, M. Magnin. Relearn Faster and Retain Longer: Along With Practice, Sleep Makes Perfect. Psychological Science, 2016; DOI:10.1177/0956797616659930

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