One of DC Comics' first superheroes, he was created by Gardner F. Fox and Bernard Christman and made his debut in "Adventure Comics" #40 in April of 1940.

Wesley Dodds was born rich, bookish, and frightened of his stern and aloof father. After his mother died, Wesley was sent to live abroad, mostly staying with people his dad did business with -- mainly in the Far East, where he learned yoga and a number of languages and martial arts techniques.

He graduated from Princeton with honors, but he began to have bizarre nightmares about criminals, injustice, and an imprisoned man in a strange helmet. Though Wesley didn't know it, the man was Morpheus, the Sandman himself, whose imprisonment by Roderick Burgess was causing bizarre dreams and sleep disorders worldwide. Fearing that his nightmares would drive him mad, Wesley took his dreams as inspiration to start working against injustice and crime.

He bought a number of gas masks similar to Morpheus' helmet and developed a green gas that functioned as both a truth serum and a sleep gas. Wearing the gas masks, a trenchcoat, and a fedora, and firing his sleep gas through a specially-designed gas gun, Wesley became the Sandman in 1938 and began fighting crime in New York City.

Wesley later met and fell in love with Dian Belmont, the daughter of a district attorney. Dian discovered the Sandman's secret identity and began assisting him on some of his cases. He later became a founding member of the Justice Society of America (and started wearing more stereotypically superheroish costumes, which I never ever liked -- that original retro gas-mask-and-fedora look was cool) and even acquired a sidekick -- Sandy Hawkins, who was known as Sandy, the Golden Boy. Sandy eventually became the ward of Dian Belmont, and since Dian and Wesley had been shacking up together long enough to become common-law husband and wife, Sandy became the equivalent of Wesley's son.

The Sandman later joined the All-Star Squadron, but began to curtail his superheroing activities after suffering a heart attack. Sandy was also gravely injured when a "silicon gun" he was working on exploded and mutated him into a giant sand monster. Wesley placed Sandy into a state of suspended animation and worked for nearly fifty years trying to cure him. During this time, Wesley was also using his fortune to better society, and Dian became a best-selling author, even winning the Nobel Prize for Literature.

Sandy was eventually captured and cured, completely by accident, by a supervillain -- since he hadn't aged in the time that he'd been transformed, he is still in his early-to-mid-twenties. He has become a silicon-based life form and adventures under the codename of Sand with the current incarnation of the JSA. Wesley, however, had suffered a stroke and finally retired from crimefighting. However, retirements in comic books are never completely permanent, and the Sandman was cast, along with the rest of the old Justice Society, into an alternate reality, where they had to battle the Norse gods for two whole years! After they got out of that, Wesley immediately had another stroke, and after that, he was aged to over 80 years old by the villain Extant in DC's Zero Hour crossover.

After Dian died, Wesley was stalked and attacked by a supernatural menace called the Dark Lord. Fearing that the Dark Lord wanted to use him to gain more power, Wesley threw himself off a cliff and died. Not that death in comics is in any way permanent, as he has made a couple of revivals since then.

Research from http://www.comicboards.com/dcguide/Who/Sandman1_Bio.htm