Understanding ATP, Fatigue, and Sleep: The Role of Cell Energy and Rest

[fanieh]

When our body cells are full of ATP (fuel from our mitochrondria), they are supposed to energize our biological systems.. but why do we feel fatigue when we don't sleep when we still have sufficient or ample supplies of ATP?

What really cause fatigue?

 

[jim mcnamara]

This is a large subject - too much for the forums here. LOTS of things cause fatigue.
Some examples:

There is clinical fatigue - a chronic problem associated with disease or deconditioning or a host other factors.

There is muscle fatigue - what you are talking about. Example: Go to the gym and do a single weight training exercise until you cannot do any more. The muscle group is fatigued.

There is a diurnal rhythm associated with periods of fatigue - sleep and wake which is related to day/night cycles and brain neurotransmitters - things like melatonin. Day/night in many urbanized countries is obscured by artficial electric lighting which the brain interprets as daylight. Can cause sleep disorders. Many animals and plants respond to day length (winter/summer) as well.google:
diurnal rhythm (beware of pill peddler sites, general NIH (pubmed) is your best bet.)
------ An example is the mass problems adjusting to daylight savings time changes due to disruption of the sleep cycle.

search the NIH site for fatigue - https://www.ncbi.nlm.nih.gov/pubmed/17370370

resistance training fatigue study - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3867092/ This is the only one that comes close to your question - ATP is involved. ATP is not a major player at all except in very limited circumstances, like this one. Actually it involves anaerobic respiration and the production of lactate.

There are also neurological diseases - narcolepsy is an interesting one to learn about - awful to have.
https://en.wikipedia.org/wiki/Narcolepsy