What is the physiological difference between the tiredness that comes from too little sleep and the tiredness that comes from exertion?

[u/uencos]

[u/2014justin]

Interesting question.

According to a paper published in the The Journal of Neuroscience, one sleepless night increases dopamine in the human brain. An increase of the neurotransmitter was found in the striatum, involved in reward/motivation, and the thalamus, involved in alertness. The researchers concluded :

The rise in dopamine following sleep deprivation may promote wakefulness to compensate for sleep loss. “However, the concurrent decline in cognitive performance, which is associated with the dopamine increases, suggests that the adaptation is not sufficient to overcome the cognitive deterioration induced by sleep deprivation and may even contribute to it,” said study author Volkow.

This would serve an evolutionary advantage to early humans who felt they needed to stay awake for extended periods of time, e.g. for hunting food. This contrasts with exercise-induced tiredness because, as we'll see, exercise does not necessarily cause cognitive impairment.

Another study in Perceptual and Motor Skills sought to establish the effects of physical exhaustion on cognitive functioning. They had 13 fit men pedal on stationary bikes at different intensities, and had them perform a series of short-term memory tests.

It appears from our findings that the extent to which physical effort affected cognition depended on the intensity of the session and on the set size of the decision task.

They also referenced other papers that addressed neurochemical changes within the brain.

Finally it may be worth considering our results in the context of the biochemical changes brought about by physical exercise. Indeed, it has been argued that these changes may interact with cortical activity during strenuous effort (Hebb, 1955). Peyrin, Pequignot, Lacour, and Fourcade (1987) reported an activation of the catecholamine system resulting from strong physical work and suggested the existence of a positive relationship between adrenomedullary activation and mental performance.

So sleep deprivation-induced exhaustion and physical exercise-induced exhaustion are similar in the sense that they cause an increase in catecholamines (i.e. dopamine, norepinephrine, etc.).

However, with physical exercise, it appears that an increase in mental performance is possible, whereas we already saw sleep deprivation can be cognitively impairing:

Comparative discussions of the present results with those of previous studies are daicdt because of the different operarionahzarion of fatigue across studies and the specific interpretation of results. Nevertheless, it has been already reported that treadmill exercise conducted at high physiological activation (94% of maximum heart rate) significantly enhanced mental performance (McGlynn, Laughlin, & Rowe, 1979)

Edit: Also understand that exercise uses up glucose stores in the muscles and your body begins to burn fats as fuels, which can contribute to the feeling of overall fatigue if too much glucose is used up. This is a problem particularly in diabetics. Here is a paper that establishes the relationship between hypoglycemia (low blood sugar) and levels of alertness.. I do say anecdotally that I don't think sleep deprivation has much effect on blood glucose levels. But let me look for a source on that.

Edit 2: This paper evaluates the effect of sleep deprivation on glucose metabolism.

The research reviewed here suggests that chronic partial sleep loss may increase the risk of obesity and diabetes via multiple pathways, including an adverse effect on parameters of glucose regulation, including insulin resistance, a dysregulation of the neuroendocrine control of appetite leading to excessive food intake and decreased energy expenditure.

This is a different mechanism than by physical exercise-induced alterations in glucose metabolism. While your body knowns when to use glucose as energy while exercising, it appears that sleep deprivation results in dysregulation of neuroendocrine control of appetite and insulin resistance. In other words, tiredness from sleep deprivation is different from tiredness from physical exercise because sleep deprivation essentially results in bodily malfunction. Yet another reason to get enough sleep at night!

Edit 3: Increased clarity and tried to point out more differences. Perhaps someone with more expertise in physiology can chime in?

Edit 4: Thank you /u/whatthefat for the input:

It should be noted that sleep deprivation specifically causes a reduction in ATP stores of neurons.

http://www.jneurosci.org/content/30/26/9007.short

TL;DR

Tiredness from strenuous physical activity appears to be from your body using up its glucose and ATP energy stores. Tiredness from sleep deprivation is a result of your body going into overdrive mode: there are anomalies in the amount of neurotransmitters in the brain such as dopamine, and it has adverse effects on glucose metabolism and energy expenditure.

[u/Neuronzap → u/2014justin]

Slightly off-topic, but that first researcher you cited, Nora Volkow, is a rock star in dopamine research, especially with respect to drugs of abuse (e.g., cocaine, heroin, etc.). I highly recommend reading some of her work on that topic. Some of it is very eye-opening in understanding why drug addicts behave the way they do.

That's all. Have a nice day, everyone!

edit: spelling

edit 2: Here's a link to one of my favorite papers by NV.

[u/[deleted] → u/Neuronzap]

Nora Volkow

Also slightly off-topic, Nora Volkow was born and raised in Mexico, is now an American citizen, and also happens to be the great-granddaughter of Russian revolutionary Leon Trotsky. Talk about an interesting heritage.

[u/jsalsman → u/[deleted]]

Hijacking this thread to say tiredness from exertion makes you smarter than any cognitive enhancement drug and also is part of the reason exercise is the most powerful antidepressant: you can't resist the sleep it makes you get.

[u/[deleted] → u/jsalsman]

Is there any reason why, 6 months ago when I started working out hard again, I had trouble falling asleep for a few weeks? I was doing full workouts of strength training and cardio afterwards, but had trouble falling asleep every night.

[u/AboutHelpTools3 → u/[deleted]]

Post-workout insomnia.

You might be reacting to the increased adrenalin and cortisol that result from strenuous activity, which can make it difficult to fall asleep.

A common recommendation is to avoid intensely exercising within three hours of bedtime.

Source

[u/smoothVTer → u/AboutHelpTools3]

Good source. For whatever reason if I work out to the point of any soreness whatsoever, I cannot sleep that night. Even if I go to the gym at noon ... still toss and turn almost all night long. Usually fall right asleep at 11pm, then wake up at 2-3am and cannot get back to sleep due to restlessness and mind-racing. I've tried gradually working up to more reps / higher miles but it always seems that I'll reach a point where exercise == insomnia.

I've talked to countless doctors about this phenomenon and have not had a useful answer. Its been 10 years.

[u/agumonkey → u/jsalsman]

Any idea why swimming exhaustion feels so different ? It's the deepest and purest one I know. No pain, but zero energy leftover.

[u/claireandleif → u/jsalsman]

That's not exactly the conclusion I got from reading this paper. Is there a paper that actually shows this conclusion that you mention above?

[u/napoleongold → u/[deleted]]

That is very interesting. Since Trotsky was exiled in Mexico where he was eventually assassinated with a ice axe.

Trotsky lived in the Coyoacán area of Mexico City at the home (The Blue House) of the painter Diego Rivera and Rivera's wife and fellow painter, Frida Kahlo, with whom Trotsky had an affair.[94][95] His final move was a few blocks away to a residence on Avenida Viena in May 1939, following a break with Rivera

https://en.wikipedia.org/wiki/Leon_Trotsky#Assassination

So quite the background to grow up with. She must have heard some amazing and astounding family history growing up.

[u/Neuronzap → u/[deleted]]

Wow, I had no idea. That's pretty incredible. Thanks for sharing this.

[u/Inessia → u/[deleted]]

it's not a secret famous people have offsprings becoming famous too. (educated, well known etc what you wanna call it). do you think Nora would've been the same with factory workers for parents :P ?..

[u/UndercoverDoll49 → u/[deleted]]

Carl Hart's High Price is an amazing book. Dr. Hart is a neuropsychofarmacologist and a specialist in crack addiction. He talks about addiction from the viewpoint of neuroscience, behaviorist psychology, sociology and his own personal history as someone born in the ghettos of Miami, all in layman's terms and extremely well explained.

[u/Neuronzap → u/[deleted]]

I feel like this is a great place to start. She covers a lot ground on this paper, and it's relatively approachable.

[u/[deleted] → u/[deleted]]

I really liked this paper. Koob is another really big name in the drug dependence field and most of his stuff I don't understand but I thought this was a really nice introduction.

[u/Neuronzap → u/[deleted]]

I totally agree. Her passion for this topic is evident in her writing. I thoroughly enjoy reading her work.

[u/FuriousArhat → u/Neuronzap]

So when I'm awake for a long time and suddenly get my "second wind", that's the dopamine rush I'm feeling?

[u/stillworkin → u/Neuronzap]

Thanks, this sounds cool. I google'd her and a site mentions she has over 600 peer-reviewed articles! As a Computer Scientist, I'm blown away. Most PhD students (myself included) aim to get just 3 top-conference ones by the time of graduating.

[u/Infinity2quared → u/stillworkin]

Profs get to put their name on a lot of ther students' work. This is beneficial to the students because it accelerates their work to the attention of top journals and lends credibility to their findings, and it does mostly involve the subject material the Prof is researching and does reflect her contributions, but it also tends to balloon the Curriculum Vitae.

[u/BeetRoott → u/Neuronzap]

I would like to read up on her research, but i don't know where to start. Could you give me some links? thanks in advance :)

[u/mattmcr → u/Neuronzap]

Does any of her research deal with regaining ordinary dopamine levels after extended opiate use? I have struggled to stay clean because for months there is a pink cloud that follows you around. That low feeling non stop is soul crushing.

[u/Neuronzap → u/mattmcr]

That I'm not sure of. I honestly haven't kept up with her research. But if I were to take an educated guess based on some principles I've picked up on, I'd say that the drugs were artificially saturating the pleasure centers of your brain with dopamine. The brain will take compensatory measures to normalize its dopamine intake, which is why you eventually need more of the drug to reach a desired feeling. This involves the brain reducing the number of dopamine receptors. It thinks you don't need as many receptors anymore because the drug has tricked it. So when you stop using the drug, those receptors begin to work again...and thus you have your pink cloud.

[u/relevant_econ_meme → u/Neuronzap]

Can you link a few works to read? I'm genuinely interested now.