Sleep, Insulin, and Alzheimer’s Disease

By Jonathan Somayajulu

For most of us, sleep is important. It’s what recharges us and gets us going for the next day. However, sleep is most often overlooked and neglected by most people my age (aka every college student ever). Most would be hard pressed to say that they haven’t neglected precious sleep in order to cram for a final or get an assignment done before that 8AM deadline. And most of us never think about the effects on our body when do this. But what are the consequences of losing sleep when we’re trying to finish that final paper on time? Turns out, it’s not pretty. Lets talk about the importance of getting enough sleep: and what happens when you don’t get enough.

Lets take a closer look at what happens when you catch those precious z’s:

When you sleep, your body goes from work mode into repair mode. It begins to detoxify your body, digest food, and store energy. When you are sleeping, your brain detoxifies and cleans out its cells (neurons) by flushing the intracellular space with intercellular fluid. This process also affects the formation of amyloid plaque which causes Alzheimer’s disease, as the flushing process clears amyloid protein from the synaptic cleft, which prevents plaque from forming. When you don’t sleep, this process doesn’t happen, and results in the buildup of this plaque over time. When this plaque builds up into a gum like consistency, the neuron eventually dies due to the blocking of the synaptic cleft (the main signal transduction pathway in a neuron). When enough neurons die off such that memory and cognition is affected, the first symptoms of Alzheimer’s disease are evident.

Insulin also plays a key role in the prevention of Alzheimer’s disease. Insulin is one of the few hormones that can cross the blood brain barrier, and is shown to regulate the formation of amyloid plaque in various studies, as well as play a role in facilitating cognitive function (Watson, et al.). While you are sleeping, the pancreas releases insulin to trigger the storing of glucose for energy in the form of glycogen in the liver. This is super important to ensure proper function of your body. When you are sleep deprived, insulin effectiveness decreases, and the pancreas puts out more and more insulin to compensate, which can lead to insulin resistance. When insulin effectiveness is decreased, its effectiveness in inhibiting amyloid plaque production is significantly reduced, and this has adverse effects on memory and cognition in the long term as well as directly leading to Alzheimer’s disease. So sleep is crucial to maintain the effectiveness of insulin, which is essential to preventing Alzheimer’s disease!

So long story short, getting enough sleep is vital to your health, and can help prevent a myriad of problems in the future. So the next chance you have, get that extra hour of sleep in: it just might save your life!

References:

Watson, G. S., & Craft, S. (2003). The Role of Insulin Resistance in the Pathogenesis of Alzheimer’s Disease [Abstract]. CNS Drugs, 17(1), 27–45. doi:10.2165/00023210–200317010–00003

Javaheri, S., Storfer-Isser, A., Rosen, C. L., & Redline, S. (2011). The Association of Short and Long Sleep Durations with Insulin Sensitivity In Adolescents. The Journal of Pediatrics, 158(4), 617–623. http://doi.org/10.1016/j.jpeds.2010.09.080