After Hayward, Wis., electrician Timothy Brueggeman froze to death while sleepwalking barefoot in his underwear Monday night, authorities were initially baffled. ...Going through Brueggeman's bedroom, investigators found a possible answer -- a bottle of Ambien. The most-prescribed sleep aid in the United States has helped millions, but it has also has been linked to hundreds of cases of sleepwalking, sleep-driving and even sleep-shoplifting. Such cases led to a class-action suit against Sanofi-Aventis. The drugmaker, which maintains that Ambien is safe when taken correctly and not mixed with alcohol or other drugs, didn't respond to requests for comment Wednesday.