Zocor May Cause Sleep Problems In Patients

A new study from the University of California at San Diego School of Medicine suggests that simvastatin, also known as the cholesterol-lowering drug Zocor, may interfere with sleep patterns: “people who took the statin drug Zocor or simvastatin found they had significantly worse sleep quality compared with people who took Pravachol or pravastatin, another cholesterol-lowering drug.” Simvastatin is fat soluble, which means it can more easily penetrate cell membranes and mess with brain chemistry.

Incidentally, Zocor is the cholesterol-lowering drug that recently lost its patent protection, leading to a burst of business for the generic version of simvastatin and a steep drop-off in profits for competitor and market leader Lipitor. (For the record, Lipitor is a third kind of statin, called atorvastatin.) Pfizer, the maker of Lipitor, has been trying hard to persuade consumers to not switch to generic Zocor—maybe now they have a new bit of ammo to use in their argument, at least for those who aren’t getting any rest.

“Sleepless? Maybe it’s your statin” [Reuters]

“Pfizer Launches Campaign To Warn Users Away From Generic Competitor”
(Photo: Getty)


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  1. BigNutty says:

    These drug studies like to use the word “may” in describing their conclusions. I don’t believe in many of these “studies” as announcements tend to draw attention to the people who conduct the survey.

    So this study just happens to come out when it would help Pfizer the most? Was this a coincidence?

    I believe when Pfizer warned against switching to a completely different generic drug they had a legitimate reason to announce that news, but now question the timing of this study.

  2. I agree that the timing is suspicious, and wonder whether Pfizer provided any financial support to the university, but wasn’t able to find any info re. that.

    However, I think all respectable studies by default would use words like “may” and “possible” because, this being science, that’s the best they can offer. It’s up to other researchers to replicate the studies and see whether they get the same results. But IANAS (scientist).

  3. RvLeshrac says:


    “I don’t think that word means what you think it means.”

    Chris Walters is right. Any respectable scientific study reports research results in “may”/”appears to”/”a factor” uncertainty. This is because the study may have some flaw that the researchers didn’t catch. If the subjects were all drawn from the same city, for example, it may turn out that there’s something in the local water, air, or food that affects the drug – you can’t account for every possible variable.

    You also have the problem of things like positive and negative bias, which are sometimes very difficult to detect when unintended.

    This is why the public has such a difficult time accepting scientific research. People seem to be of the (insane or stupid) mindset that nothing in science changes. As scientific tools and knowledge improve(s), we frequently discover new evidence which can either add further weight to prior research or overturn its results. Add to that the current popular climate, where changing one’s mind based on the evidence available to you is somehow undesirable (again, insanity or stupidity), and you have a rather troubling mix.

    Health/medical research is especially troubling to many people, as they want (understandably) some magical cure that will make them perfectly healthy and immortal. Science can, unfortunately, only make a very educated guess at health effects, barring long-term research – and long-term research has its own problems.

    Further, health research requires subjects that are willing to follow, to the letter, the researchers’ directions, and inform the researchers of even the smallest changes and most embarrasing details of their lives. Testing can reveal a number of factors which may affect the research, but the individuals themselves can make poor health decisions, without informing the researchers, that can skew the research in unknown ways.

    It should also be noted that the title of the article is *extremely* misleading, which is another issue, re: “people who took the statin drug Zocor or simvastatin found they had significantly worse sleep quality compared with people who took Pravachol or pravastatin, another cholesterol-lowering drug.” While I haven’t read the research, that statement is implying that it is *specifically* the simvastatin that is producing a noticable affect on sleep patterns.

    As with all medical research, one must be extraordinarily careful not to read things into the results. “Statins” are a type of drug, in the same way that NSAIDs are a type of drug but, like NSAIDs, they are not all exactly alike.

  4. darkclawsofchaos says:

    makes sense that the brain is affected since it is made of mostly fat and takes a whole ton of blood

  5. fofy21 says:

    A couple of things.

    First, statin is not a medicine, but a class of medicines. Zocor, Pravachol, Lipitor, and Crestor are all statin medicines. So the line at the beginning of the blog that goes “…suggests that statin, a drug used to treat…” should instead read “… suggests that [Zocor or simvistatin], a drug used to treat…”.

    Second, the reason the article came out now is because the research was finished now or close to now. Before the study the researchers use statistical analysis to dictate how many patients needed to be enrolled and how long the patients needed to be monitored. Once the required number were enrolled and had been monitored for the appropriate amount of time, and once all the data had been analyzed and written up, the study was submitted to be published and in this case, was submitted to be presented at a medical meeting. This is what decided when timing of the study coming out.

    The study was presented at the American Heart Association annual meeting which is going on right now. This means the study may have been done a couple of weeks/months ago, but the reason the authors waited to present the data wasn’t because it would help Pfizer, but because they got chosen to present at one of the biggest national meeting for Cardiology, and if they let the data out early, they would have been in trouble.

    It is also important to note that the study hasn’t been published in a scientific journal yet. This means the authors presented their findings in a 15 minute presentation. All the details of the data haven’t been seen by the medical community yet (only what the authors presented), so I’d be careful about making any decisions based on this report (like stopping Zocor).

    And finally, the study had nothing to do with Pfizer. It was funded by the National Heart, Lung, and Blood Institute (government research organization). In addition, none of the authors reported getting funding or support from Pfizer (or any other drug companies).

    Now I’m not saying Pfizer won’t take this information and try to push for everyone to use Lipitor, ‘cuz they will. I’m just saying there isn’t any nefarious scheme by Pfizer in regards to this study (at least that I can tell from my research).

  6. RvLeshrac says:


    Oh, and the warnings against switching drugs are meant to ensure that patients check with their physicians and take their advice (with some profit motive, obviously, as they’re a business). There’s too much advertising and flaky information out there (and Pfizer is by far not an angel) from pharmaceutical companies and the media alike, and a lot of patients will pressure their physicians into allowing them to switch drugs.

    Your physician has to be very careful about the drugs they prescribe, basing their advice on many factors in your lifestyle and physiology. Some will cave immediately to a patient’s pressure (“Well, I’ll just find a doctor who will switch me!”), and some won’t allow a switch until the patient starts making things up (“I’m suffering from [bad side-effect], I need to try something else!”).

    Different forms of a drug work differently, and switching to new medication can have *serious* consequences if you aren’t careful.

  7. dshjyd says:

    Am I the only one that read that as “Satan may cause sleep problems…”?

  8. fofy21 says:


    Dang, you must have posted while I was typing my first message. I didn’t even notice the title. I agree it is misleading (actually the more correct term would be wrong). Zocor/Simvastatin should be there in place of statin.

  9. @RvLeshrac & @fofy21: Thanks to both of you for pointing out the problems with the misleading title. I took Reuters’ lead when writing the headline even though I knew it seemed too general. I’ve gone back and edited the post so that it no longer suggests that *all* statins may be linked to sleep problems, just Zocor/simvastatin.

  10. RvLeshrac says:


    Yeah, I noticed that. :p

    Unfortunately, people will continue to do that. One of the biggest problems in the scientific community today, especially medicine, is that the reporting of studies is rarely done properly. People read something like “Smoking crack improves health” and take it at face value, without reading the actual research, which states that “Smoking crack improves the health of the carapaced Egyptian rock lizard.”

  11. @Chris Walters: And Satan.

  12. RvLeshrac says:

    @Chris Walters:

    Excellent! Thanks. Just take care in the future, and I’d try to avoid quoting media outlets as much as possible when posting medical stuffs, for the reasons I pointed out above. ;-)

  13. fofy21 says:

    I’m with RVLESHRAC on this. While I think it’s important to make sure consumers (or patients like we used to call them in the old days) are as informed as possible, mainstream media has the tendency to sensationalize scientific results, and suddenly patients are making bad medical decisions based on bad data.

    And Chris… wow, that was a quick correction. Thanks.

  14. Pfluffy says:

    Please notice that almost every single study published of new drugs shows only a correlation not definite causation. A correlation does not equal causation and the word “may” is the most cautious thing a company can honestly say without causing panic or lawsuits. It’s very hard to accurately summarize a study in the 2 minutes on a newscast or three paragraphs in a newspaper. Best advice is ignore the “news” which is usually a press release by a drug company when an anchor person introduces the faux story. Go to the journal and read it for yourself and certainly discuss every one of your health concerns with a qualified doctor AND follow up with a consultation with your pharmacist.

  15. Technick says:

    This study has perfect timing for me. My doctor just put me on the generic simvastatin (40mg) last Friday and I just started taking it Sunday. Since Sunday I’ve been having some sleep problems. Everything from my neighbor leaving his back yard light on to my cats crawling around the bed has been waking me up, something I normally sleep through.

    Guess I need to go talk with the doc and get off this stuff or pick up some Ambien..

  16. bohemian says:

    My husband was put on simvastatin recently and he developed insomnia, he also started Chantix so he wasn’t sure what one was causing it.

    Simvastatin is on all of the $4 drug lists. I went and looked and Pravastatin is also on most of the $4 drug lists. So people have at least one other option that isn’t on patent and obnoxiously expensive. Pravastatin is probably one of the water soluble ones.

    I still don’t trust the whole issue since drug companies have a habit of trying to scare people into spending more money than they need to.

  17. Hambriq says:

    I will agree in that I highly doubt that this article was part of some grand conspiracy by Pfizer.

    However, I’m not altogether surprised. Simvastatin was one of the earlier (relatively speaking) statins on the market. I have had a surprisingly high number of patients report problems with simvastatin or simvastatin containing products (namely Vytorin). Of course, it’s hard to really quantify those results in a pharmacy setting.

    Either way, it just goes to show you the importance of taking an active role in your health care and not blindly accepting the advice of flag-wavers on either side. Generics aren’t always the answer, nor are new, expensive, name brand drugs.

  18. bonzombiekitty says:

    @BigNutty: They have to use the word “may” because people don’t have the same reaction to the drug. It might, for example, interfere with the sleep patterns of 30% of people, that’s a more than significant portion of people that the warning needs to be there. Alternatively, it might interfere with the sleep patterns of 70% of people, but that 30% is significantly large to say say it may not interfere.

    You should only be using words like “will” in these sorts of studies when you’re looking at near 100%. But even then, you have to worry about unknown flaws in the study (but with a near 100% confidence, it’s not as likely).

  19. Hambriq says:


    Pravastatin is actually the most water-soluble statin.

    P.S. I just got the following email response from a colleague of mine:

    I’m surprised you didn’t know about that. Try Googling “statin insomnia”. This is old news.

    Well, there you have it.

  20. MENDOZA!!!!! says:

    Consumerist —-> Pharmarist?

  21. s35flyer says:

    Been on zocor for 6 years, I sleep just fine.

  22. dodonnell says:

    @s35flyer: I’m glad Zocor’s working for you! My doctor put me on simvastatin a few months back, and I *have* noticed my overall quality of sleep has diminished. There could easily be other factors at play than just the medicine, of course, but I do plan to talk to her about it after my next set of blood work.

    This may be “old news” to some in the medical community, but I’m really glad to see it covered on Consumerist. I might not have learned of it otherwise, and might not have thought to mention it to my doctor as a result.

  23. RvLeshrac says:


    Actually, if any study shows a near-100% correlation, it is *more* likely to be flawed. There are very tiny numbers of studies that have definitive results right off the bat, which is why we have peer-review and repeated experimentation.

  24. RvLeshrac says:


    Which means… absolutely nothing.

  25. Bryan Price says:

    That’s interesting. It might explain my changed sleep habits.

  26. Her Grace says:

    @RvLeshrac and @fofy21: I love you guys. A whole lot.

  27. gingerCE says:

    I’ve been on zocor for a year and I haven’t had any sleep problems. I sleep like the dead at night.

  28. RvLeshrac says:


    Once again, good for you, but totally irrelevant.