A million patients taking statin linked to sleep problems and weight gain

In the biggest study of its kind, U.S. scientists found simvastatin disrupts the sleep patterns of some patients, which they claim could lead to aggression and weight gain.

The drug is the cheapest statin available and has been promoted by the Government as part of its cost-cutting drive.

It is also the only statin which can be bought over the counter in pharmacies, where it is sold as Zocor Heart Pro.

The latest findings come from a study of 1,000 healthy men and women who were taking either simvastatin, pravastatin (another cholesterol-lowering drug) or a "dummy" pill.

Experts claim sleep disturbances may be triggered by simvastatin crossing into the brain, unlike some other statins.

Dr Beatrice Golomb, of the University of California at San Diego School of Medicine, said: "The findings are significant because sleep problems can affect quality of life and may have adverse health consequences, such as promoting weight gain and insulin resistance.

"The results showed that simvastatin use was associated with significantly worse sleep quality."

At present, 3.4million people take statins to cut the risk of heart attack and stroke and the cost is close to £1billion a year.

The British Heart Foundation estimates almost 10,000 deaths a year are avoided as a result.

Simvastatin is the most widely prescribed statin here because it is a generic drug - along with pravastatin - which makes it cheaper than branded versions.

The latest study compared simvastatin, which is lipophilic (soluble in fats), and pravastatin, which is hydrophilic (soluble in water).

Because simvastatin is fat soluble it can more readily penetrate cell membranes and cross the blood brain barrier into the brain.

The brain controls sleep, and many of the brain's nerve cells are wrapped in a fatty insulating sheath called myelin.

Releasing the results yesterday at the American Heart Association, Dr Golomb said: "On average, the lipophilic statin had a greater adverse effect on sleep quality."

She added: "Those who reported developing much worse sleep also showed a significant adverse change in aggression scores compared to others."

Dr Golomb said: "Patients taking simvastatin who are having sleep problems should consult their doctor. Sleep deprivation is a major problem in a minor number of people."

In past studies, some people on statins have reported having insomnia or nightmares.

In the UK, sleep disruption is not recorded as a potential side effect in product information for simvastatin or Zocor Heart Pro.

Dr Malcolm Kendrick, author of The Great Cholesterol Con, said many patients were not aware of the side effects and their concerns were often dismissed by doctors.

He said: "These side effects can include subtle effects on cognitive function including memory, sleep and aggression levels which have been highlighted by scientific research papers."

A spokesman for the Medicines and Healthcare products Regulatory Agency said there were European moves to harmonise information about the side effects.