Brighthaupt said Smith would take muscle relaxants straight from the bottle as a sleeping aid and would sleep long hours, often being asleep more than being awake.
Smith died of an accidental prescription drug overdose in February 2007.
Brighthaupt testified Monday saying that Dr. Khristine Eroshevich would provide her with medication and her mood improved.
Eroshevich along with Dr. Sandeep Kapoor from Studio City are charged with unlawfully prescribing a controlled substance to an addict. Smith's companion, Howard K. Stern, is also charged with obtaining the drugs and administering them to Smith.
The defense tried to attack the bodyguard's credibility, saying he was scheming to make money. He sold photographs of Smith and gave interviews to several entertainment shows and received tens of thousands of dollars.
Brighthaupt admitted he never told detectives about the drugs and medications until October 2007 when Stern accused him of stealing photographs.
Brighthaupt said he was disappointed and angry and that's when he gave an interview and went to detectives accusing Stern of providing drugs to Smith.
He also said Smith would often take an over-the-counter pain reliever, Panadol, somtimes five or six tablets at a time, while also taking her prescription medication.