Researchers from Uppsala University in Sweden, studied the effects of sleep deprivation in healthy young men. So, the morning after a sleep deprived night, they took blood samples from these young men. And, they discovered increased concentrations of Neuron-Specific Enolase (NSE) and S100 calcium binding protein B (S-100B) molecules in their blood.
Especially relevant was that, the NSE and S-100B molecules are usually found in the cytoplasm of neurons and glia cells located in the brain. Therefore, their increased concentrations in blood is indicative of either damage to the neurons, or impaired blood brain barrier function, or both.
In addition, the NSE and S-100B molecules have been used as biomarkers (or indicators) of brain damage. Therefore, their rise in blood after sleep deprivation indicated that lack of sleep promoted neurodegenerative processes that resulted in loss of brain tissue. However, neurons are not the only brain cells affected by sleep loss. Significant changes also occur in the brain’s oligodendrocytes, astrocytes and microglia.
Most of all, the level of S-100B protein in blood has been found to be elevated after brain cell loss. Moreover, this loss occurred because of artery blockage and subsequent lack of blood supply to the brain cells, thereby killing the brain cells. Because S-100B protein also occurs in astrocytes and oligodendrocytes, its concentration in cerebrospinal fluid (CSF) or blood has been considered a suitable surrogate marker for the diagnostic or prognostic assessment of neurodegeneration or brain damage.
So why does sleep deprivation cause neurons and other brain cells to die?
First of all, studies have discovered that wake-activated neurons are highly susceptible to degeneration. Furthermore, extended wakefulness, by reducing sirtuins (a family of proteins) in vulnerable neurons and/or brain regions, results in mitochondrial metabolic stress.
In addition, extended wakefulness, by increasing cytokine responses in vulnerable neurons and/or brain regions, results in inflammatory stress. Especially relevant, cytokines are substances such as interferon, interleukin, and growth factors that are secreted by certain cells of the immune system and which effects other cells.
Moreover, not getting regular good night sleep affects the body is other ways. And, the infographic below illustrates these.