Hangovers are caused in the main by dehydration as the salts and minerals are leeched for the cells due to the directic effect of alcohol. I knew this but I havent reached day 4/5 for a very long time, and have been astounded that im so dehydrated even after drinking water. Using a salts/mineral replacement helped today (dyoralite) which seemed to help for me.
All new ground to me too. Take care
