Sept. 30, 2011 -- Lawyers for Dr. Conrad Murray said in opening arguments this week that he was trying to wean Michael Jackson off propofol, the powerful sedative the defense says Jackson gave himself the night he died.
They allege Jackson wanted propofol because he was suffering from insomnia brought on by withdrawal from the painkiller Demerol.
Murray's attorneys plan to call an addiction specialist, Dr. Robert Waldman, co-medical director of the Recovery Unit at Daniel Freeman Marina Hospital in Marina del Rey, Calif., to testify about the singer's addiction.
"And what he's going to tell you is that Michael Jackson was suffering from the Demerol withdrawal, that his insomnia was as a result -- partly, at least as a result," attorney Ed Chernoff said during the opening statement.
Chernoff also told the court Jackson received Demerol three to four times a week from a dermatologist, Dr. Arnold Klein, but Murray knew nothing about these regular doses of Demerol. Klein didn't respond to ABC News' request for comment on the defense's allegations.
Jackson told Murray his insomnia was caused by his creative mind always racing, but it was also the Demerol, Chernoff said.
Withdrawal Symptoms Include Insomnia
Medical experts say there are numerous symptoms associated with Demerol withdrawal, and insomnia is one.
"Withdrawal is very much like suffering from the flu. You can get nausea, diarrhea, vomiting, chills, tremors, a nervous or anxious feeling and insomnia," said Dr. Michael Schmitz, professor of anesthesiology at the University of Arkansas for Medical Sciences/College of Medicine.
Chronic use of Demerol generally causes sleepiness, but not everyone experiences that effect.
"There is a sub-population that reports insomnia," said Dr. Keith Candiotti, professor of anesthesiology and internal medicine at the University of Miami Miller School of Medicine. "Probably people who are chronically on drugs would be less susceptible to sedation."
Some experts say there are a number of medications that help alleviate withdrawal symptoms, including propofol, although others argue propofol should never be used for that resason.
"Propofol and benzodiazepines have been used for managing withdrawal, but primarily in intensive care units," said Schmitz. "That's not something that would have been done at home." Benzodiazepines are medications that treat conditions such as anxiety and insomnia. Schmitz added propofol is used in this way only in very exceptional cases.
"Propofol is an intravenous anesthetic, not to be used to treat Michael Jackson's addiction to Demerol or the withdrawal he may have had," said Bruce Goldberger, professor and director of toxicology at the University of Florida in Gainesville.
Murray told police he gave Jackson only a small dose of propofol, but the defense said Jackson administered the fatal dose himself. Chernoff also said that Murray felt it was his duty to wean Jackson off the propofol and teach him to sleep naturally.
Criminal defense attorney Mark Geragos, who is not involved in Murray's trial, said Chernoff's Demerol argument is central to the defense.
"I think it's essential," Geragos said. "My interpretation of his arguments is that Jackson may have become increasingly anxious to fall asleep." His growing restlessness, Geragos added, could have led him to self-medicate.