I think the OP is referring to the drop in blood pressure which temporarily changes activity in some areas of the brain and can cause some euphoria and disassociation (which due to some level of trip memory or hppd might be reminiscent of a breakthrough for him/her)
HOWEVER THAT IS QUITE A DANGEROUS METHOD. Standing up in that state could cause you to pass out and smack your head (trust me i have done it and it isn't worth the risk).
An alternative method is by sitting down and getting your brain in to that state by hyperventilating and holding your breath (kids know this by the name of spacemonkey but it also involves standing up). Just by hyperventilating for 10 seconds and holding for 5-10 seconds can you induce that euphoria.
It works by constricting blood vessels because of the blood becoming more alkaline due to increase o2 concentrations in the blood. This then causes a temporary pooling of blood in the brain and therefore slows activity in some areas:
Decrease in partial pressure of alveolar CO2.
Decrease in partial pressure of arterial CO2.
Increase in blood pH, (respiratory alkalosis).
Vasoconstriction of blood vessels supplying brain.
Pooling of the blood present in the brain at the time.
Brain rapidly uses up oxygen (O2) available in the pooled blood.
O2 concentration in the brain drops.
Read this nexus thread for more info:
https://www.dmt-nexus.me...aspx?g=posts&t=68615