Two interesting studies were published this past week on sleep and its effects on memory and learning. Sleep disturbance is a common problem in our daily lives, 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 is going on while we sleep. Sleep helps our brain function properly, improves learning, and protects our mental and physical health. On the other hand, lack of sleep contributes to weight gain, our immune response, hormone dysfunction, and how our body reacts to insulin.
In the first study, researchers from the Netherlands and Pennsylvania discovered a component of how the lack of sleep negatively impacts memory. This animal study, published in eLife, demonstrates 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. Previous research has shown the role of sleep in memory, but this study shows that sleep deprivation impairs hippocampal function. The results indicate that lack of sleep significantly reduces the length and density of the dendrites of the neurons in the hippocampus.
The researchers repeated this sleep-loss experiment but then left the mice to sleep undisturbed for three hours, a period of time sufficient to restore deficits caused by lack of sleep. The effects of the five 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 six 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 one week later, and this benefit was still noticeable at six months. 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 patients’ sleep disturbances can be very challenging. One nutrient does not work for everyone. We all have our own biochemical individuality and there can be different underlying causes to an individual’s sleep issues, such as 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 while another compound may cause drowsiness. We also need to keep in mind, if we are recommending supplements for a child or a pregnant woman, we may want to avoid certain botanicals, neurotransmitters, and hormones.
By Michael Jurgelewicz, DC, DACBN, DCBCN
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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