Taking a daily dose of dark chocolate could be beneficial for those suffering from chronic fatigue syndrome or ME, according to a new study.

Research found that patients who were given a daily portion of high cocoa content dark experienced fewer fatigue symptoms than those who were not given the dose.

The study came about after a patient of Professor Steve Atkin, an expert in endocrinology, said that she had felt better after swapping her usual treat of milk chocolate for the cocoa-rich dark variety.

Professor Atkin said he was very surprised at how much effect the chocolate seemed to have - two of those involved in the study were able to return to work after having been signed off for six months.

Researchers from Hull York Medical School think that the key to the chocolate's success in alleviating symptoms could be its effects on levels of the chemical serotonin in the brain.

Professor Atkin explained: "Dark chocolate is high in polyphenols, which have been associated with health benefits such as a reduction in blood pressure.

"Also high polyphenols appear to improve levels of serotonin in the brain, which has been linked with chronic fatigue syndrome and that may be a mechanism."