When your child stays up all night working on a massive lego project and in the morning he/she has symptoms similar to that of an alcohol induced hangover: Sleepy, irritated, irrational, nauseous, thirsty and hungry. Adults may experience mild to extreme symptoms when building or helping children build a Lego project that requires hours upon hours of building. This can be prevented by reading the Lego box carefully. If the Lego has a reccommended age of 16+ you are very likely to experience a Lego hangover upon completion of said project.