This easily explained:
Ketamine seems to repair some kind of cell damage, thereby increasing neural plasticity.
That is a huge asset, but long endured depressions leave many unhealthy neural circuits over the years. These have be unlearned one by one, which takes time.
Ketamine increases freedom of thought and emotion, but you still need a goal and long-term plan to precisely target and unwork all the patterns that circle back to depression.
Luckily the entrypoint away from happiness is discernable and it is bittersweet: giving up, thereby reducing stress. Which is sweet at first, but turns into hell fast.
Neuroprotective behavior is one of the theories I've heard about ketamine's efficacy, as well as lithium's, but that doesn't explain the immediate gross improvement, just the eventual semi-permanent tolerance in some cases.
In my case, while it was effective, I was a much more productive and healthy person than I'd ever been, cleaning up lots of mess and accumulated dross I'd never been able to convince myself to go through, more physical activity, more consistent eating...but then it all abruptly came crashing down, eventually, so either the learned behaviors have quite a thresholding behavior, or it's a more complex mechanism.
Humans feature meta-cognition. I suspect you felt better and more relaxed due to the mechanism, and that in turn gave you another big boost by showing you that you are still capable to feel and act different.
There is a nice scene in the documentary "Le route de l'opium", where they interview, I believe the guy responsible for europol drugwar coordination. They ask why the laws and system are like this if they are so incredibly stupid and not working.
His answer: Because this is the way many individuals earn the most money with it. Change anything and manufacturers, dealers, corrupt politicians etc. would lose money.
An exam-question a german lawyer told me to illustrate how layman's understanding of law and expectation of logic therein often doesn't apply:
"Your employer tells you to break into an opponent's office and steal something. You do that, jump out of the window and break a leg. Is your workplace insurance legally obliged to cover the medical cost?"
There is a theory about epilepsy that systems that compare actual perceived state with projected state break down. Psychedelic experience might be similar.
So my interpretation: Instead of perceiving something happening to you (in time), you perceive everything to "be you". Instead of critically thinking about if and why something makes you laugh the thing itself because the laugh.
I work together with a psychology professor (was head of department) now and then. She said there's a large problem with students, even graduates, just not understanding statistics and math properly (or at all)
I was very sick as a child: I had neurodermitis (Lichen simplex chronicus) so I was constantly scratched bloody. I also had asthma and countless plant, animal and food-allergies, so I couldn't eat most things (dairy-products, sugar in every form except honey, salt, chocolate, white flour, eggs, nuts, citrus-fruits, the list goes on and on). Spent a lot of time in hospital.
When I was about 9 or 10 years old I got to a point where I was completely fed-up by all the rules I had to follow: Eat this. Don't eat this. Be careful during sports because of your asthma. There's ozone in the forest.
So I decided to ignore every single symptom until it got so strong that I'd have to go to hospital again. I also started showering cold every day and trained myself to sleep without a blanket, so I wouldn't sweat, which would irritate my skin.
I don't know when it happened, but all my problems completely disappeared over time. I'm 30 now, tests I do now and then, say my allergies and asthma are still there, but i'm more or less symptom-free.
Whenever I feel bad I consciously use the placebo-effect, for example by drinking a large glass of water and telling myself that THIS glass of water is EXACTLY what my body needed right now and will make everything better.
Note that I'm not advocating to reduce medicine: When I have a headache, I'm the first to take an aspirin. All I'm saying is that there's definitely a large cognitive component in health and feeling well, which can be trained.
The main emotion involved in procrastination is disgust. A basic emotion that is as strong as fear, but is completely learned and can be attached to every kind of situation, activity or just the thought of starting them.
Procrastination is protecting yourself from feeling the upcoming revolting disgust these activities can bring. You avoid feeling it, like you avoid touching a hot plate, that's why the disgust never shows. Only when somebody forces you to do it anyway.
The (scientifically tested) theory for this is called Anstrengungsvermeidung (german for "effort/stress avoidance") and isn't widely adopted.
That is a huge asset, but long endured depressions leave many unhealthy neural circuits over the years. These have be unlearned one by one, which takes time.
Ketamine increases freedom of thought and emotion, but you still need a goal and long-term plan to precisely target and unwork all the patterns that circle back to depression.
Luckily the entrypoint away from happiness is discernable and it is bittersweet: giving up, thereby reducing stress. Which is sweet at first, but turns into hell fast.