Scots are being asked to reveal their drinking and drug using habits to show how the country compares to other parts of the world.
Researchers are hoping the survey will paint a realistic picture of the way people indulge in alcohol and other intoxicating substances. The study poses a number of questions, including asking drinkers how much they need in order to feel tipsy.
The Global Drug Survey, which is the largest of its kind, is taking place over the next month in 20 different countries. Last year it found a third of the working Scottish population had turned up to work under the influence of alcohol or drugs. Scotland was also one of the worst three countries when it came to the number of people hooked on alcohol - but many of these problem drinkers thought their habits were normal.
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This year's survey aims to tease out how much people think they need to drink to enjoy themselves. It will also probe how drugs are used in a number of other ways, from legal highs to substances which are believed to aid slimming, athletic performance and cramming for exams.
Adam Winstock, a consultant psychiatrist, lecturer at King's College London and the founder of the Global Drugs Survey, said: "I think some Scottish people may take comfort in the perception that everyone drinks, but actually the picture isn't as bad as they think. Not everyone does go out and get bladdered.
"The problem with alcohol guidelines is they do not let you get drunk, or not very often, and therefore people dismiss them."
To complete the survey go to www.globaldrugsurvey.com/GDS2015