As every basketball fan knows, there was only room this week for news of upsets, overtime games, and three pointers. One set of headlines, however, caught my eye. "Shift workers beware: Sleep loss may cause brain damage, new research says" , "Lost sleep leads to lost brain cells", "Lack of Sleep Kills Brain Cells, New Study Shows".
As I read through the fuzzy descriptions of LC neurons and SirT3 levels, I realized that everyone following March Madness should also be able to understand the detailed Journal of Neuroscience paper I worked my way through.
The premise of the study focuses on a group of neurons, the locus ceruleus (LC) neurons that are metabolically active when a person is awake for a long period of time. For those neurons to function optimally, there is a specific level of SirT3 that must be maintained. The study shows that after sustained periods of wakefulness, the level of SirT3 decreases and a percentage of LC neurons are lost.
As I read the paper, I was reminded of this year's tournament. The big upsets (Duke, Villanova, Syracuse, Kansas) have had sustained periods of time at the top. Yet this year, all three teams played carelessly and didn't quite maintain the level of play they needed to. It is a clear analogy to LC neurons (the teams) and their gameplay (SirT3) that allows us to think about this research in a critical and meaningful way.
We can analyze this paper and the findings the way we might analyze a basketball loss. In basketball, we see only the game being played on the court. In research, we can only read the paper and interpret the data we are given. In both, we can ponder the external things (i.e. the new foul rules) that may have had an impact or that were not adequately tested. The more basketball you watch, the better you become at understanding the game. It's the same way with research papers.
There were two big questions I had while reading the sleep deprivation paper. First, did the sleep deprivation of the mice contribute to stress or were there any other environmental factors that may have resulted in the loss of LC neurons? Second, was the loss of LC neurons significant enough to have a permanent and noticeable impact on brain function? The authors of the paper conducted several experiments to rule out stress and other environmental factors as a possibility, which validated their work considerably. However, while the connection between a loss of LC neurons and several neurodegenerative diseases has been established previously, it remains to be seen if the level of damage is enough to cause a noticeable and permanent impact on brain function.
So yes, a loss of sleep does appear to result in a lack of SirT3 that appears to drive a loss of LC neurons. Is it something a shift worker should quit their job over? Not until we know the level of impact, and how long it may last. It would be analogous to if next March, we all had Duke losing first round because it did this year. There are still many factors to quantify and understand.
Sleep has been shown to be important before -- this study doesn't hugely build on that beyond providing physical proof of the impact in the brain. However, there is still a lot that we don't know -- there may be an adaptive shift over time that changes this trend for LC neurons, SirT3 level changes may have other consequences that were not tested for, and the glaring mice and human differences that may exist.
Personally, I am hoping that sleep loss isn't a direct cause of permanent brain damage; the irony of working on this article while taking a "red-eye" flight has not been lost on me!