[garganzol]

Fatigue is not only a mental thing as many assume. What really happens is our cells are gradually accumulating Reactive Oxygen Species (ROS) while we are awake, and when a certain threshold of ROS is reached, we feel tiredness.

This is a defensive mechanism of a living organism to keep ROS levels at bay. But what happens if one ignores the fatigue? ROS cellular levels will continue to climb up to the point of a pathological cell destruction. The thing is ROS are chemically active and when there are too much of them, you are asking for problems. Such as: broken enzymes in mitochondria, overoxidized lipids, damages of DNA and mtDNA - it all starts to accumulate. This is when a fatigue may gradually transform into one of the physical diseases. Cardio-vascular problems, T2DM, cognitive impairment, ME/CFS. The list go on and on [1].

So, if you often feel tired then you should be very aware of the underlying biochemical processes. It's all mental until it's physical and hardly reversible.

[1] https://en.wikipedia.org/wiki/Sleep_deprivation

[2] https://hms.harvard.edu/news/sleep-death-gut

[copperx]

I've never heard of this before. Is this well known? Do ROS go away after sleeping?

[garganzol]

This is relatively well known [1]. ROS normally go away after sleeping, and this one of the reasons we need sleep.

But. If you are past a certain threshold, ROS can do so much damage that it starts to affect cellular ATP production, leading to a tissue hypoxia. When this happens, it leads to onset of an acquired mitochondrial dysfunction. This is a pathological state that is characterized by a lingering fatigue as its main hallmark sign. Such fatigue does not go away after sleeping.

But usually it is not like 0 or 1. A person may have something in between and live without even knowing it, thinking that it's all just mental or age-related.

[1] https://pubmed.ncbi.nlm.nih.gov/27285492/

[copperx]

I wish I had heard about this earlier. I'm now 40 and my sleep patterns are not healthy. I don't have insomnia, I'm just used to sleeping past the point of total exhaustion. That cannot be good given what you say about ROS :(

[rramadass]

Can you suggest a good overview book on this subject?