Heinrich Hoffman (June 13, 1809 - September 20, 1894) was a German psychiatrist, born in Frankfurt-am-Main and studied at Halle; after graduating, he became a general practitioner in Frankfurt. Hoffman wrote books on medicine and psychiatry but became a well-known writer thanks to Der Struwwelpeter (1845), translated into English by Mark Twain with the title Slovenly Peter. This book has been translated to many languages and is now considered to be a children's classic, despite being unconventional and against any "politically correct" principles. Hoffmann also wrote poetry, humor, and satire.

Hoffman was first to describe Attention-Deficit Hyperactivity Disorder (ADHD) in 1845 in a fun poem.
"But Fidgety Phil / He won't sit still; / He wriggles / And giggles, / and then, I declare, / Swings backwards and forwards, / And tilts up his chair."

References

• Hoffmann at wikipedia