Nibiru
Bluelighter
There's also tons of hours of incredible and deep silence where staring at a wall your brain transforms (DMT and 5-meo-DMT release) and you feel things click into place. This is called 'samadhi' and can be experienced in degrees.
I've experienced samadhi and I've experienced heavy DMT trips, and would have to say that they are strikingly close, but I wouldn't say that the experience of samadhi is caused by endogenous DMT. Whether or not DMT actually has a function or is a metabolite or intermediate or a genuine neurotransmitter is unproven. Given the fact that a number of compounds can produce intense psychedelic experiences that all have a serotonergic effect, I could almost believe that a very specific, localized and heavy release of serotonin itself is responsible for the state of samadhi. Although this could be mediated by a release of endogenous DMT, I'm not convinced.
What I find super interesting is the relationship between concentration and regular practice and the ability to achieve a deep meditative state. This would have a lot to do with modifying the reward pathways, and I think that a lot of insight could be gained from recognizing the relationship between the reward system and the serotonin system.