“Hangover researchers have three options, all of them flawed. First, experiments in other animals, which are both ethically suspect and of questionable validity, given the uniquely human factors that contribute to the creation of hangovers.
“Second, laboratory experiments with willing volunteers under controlled conditions. These again fail to reproduce environmental factors and also introduce an observer effect; people do not behave normally if they know they are being watched.
“Third, self-reporting of hangover symptoms combined with tests performed the morning after – about the last time anyone is capable of supplying reliable answers.”

“Regrets? I’ve Had a Few …”
Richard Webb
New Scientist
December 2016