Nov. 7, 2007 (Orlando, Fla.) -- Are you tossing and turning at night? A popular cholesterol-lowering drug may be to blame.
In a new study, those who took the statin drug Zocor reported they had a significantly worse quality of sleep than those who took a placebo or Pravachol, another statin drug, says researcher Beatrice Golomb, MD, an associate professor of medicine at the University of California, San Diego.
"Problems with sleep initiation, problems with sleep maintenance, a feeling that sleep was unrestful, and napping during the day -- none of those actually were what was going on," Golomb tells WebMD.
So what's left?
Maybe nightmares, something related to sleep-disordered breathing, or some as yet unexplored problem, Golomb says.
"Although the average effect on sleep was detrimental on Zocor, this does not mean that everyone on Zocor will experience worse sleep," she says.
They were randomly assigned to Zocor, Pravachol, or a placebo for six months. Participants rated "sleep quality" and "sleep problems" on two standardized sleep scales.
Insomnia is listed as a possible side effect on the labeling of all statin drugs.
The findings were reported at the American Heart Association's (AHA) Scientific Sessions 2007.
The National Institutes of Health funded the study.
Fat-Soluble vs. Water-Soluble
Zocor and Pravachol dissolve in the body differently, says Gordon Tomaselli, MD, chairman of the committee that picked the studies to highlight at the meeting. Tomaselli is chief of cardiology at Johns Hopkins University School of Medicine in Baltimore.
Zocor dissolves in fat, so it can more easily penetrate cell membranes and cross the blood-brain barrier into the brain. Pravachol dissolves in water, so it has a hard time penetrating these barriers.
"It's easy to theorize that if you get a foreign substance in the brain, it might affect sleep, cognition and other processes controlled by the brain," Tomaselli tells WebMD.
Merck, the maker of Zocor, says in a statement that it conducted sleep studies with Zocor, Pravachol, and a placebo and found no difference with regard to sleep disturbances between Zocor and the placebo.
Additionally, in a study of more than 20,000 patients, people taking Zocor were no more likely to stop taking it because of sleep disorders than those on placebo, Merck says.