Eating a Mediterranean diet or other healthy dietary pattern - comprising fruit, vegetables, legumes and nuts and low in processed meats - is associated with preventing the onset of depression, according to new research published in the journal . The study involved more than 15,000 people and compared three diets: the Mediterranean diet, the Pro-vegetarian Dietary Pattern and Alternative Healthy Eating Index-2010. Lead researcher Almudena Sanchez Villegas, of the University of Las Palmas de Gran Canaria, says these diets have a positive effect on mental health. "The protective role is ascribed to their nutritional properties, where nuts, legumes, fruits and vegetables (sources of omega-3 fatty acids, vitamins and minerals) could reduce the risk of depression," the study says. The participants were polled on their diets and lifestyle in 1999 and again about 10 years later. However, the benefits have a threshold: a moderate adherence to these healthy dietary patterns was associated with an important reduction in the risk of developing depression, but the reduced risk plateaus even if participants were stricter with their diets and eating more healthily.

A double espresso in the evening delays the internal circadian clock that tells us when to get ready for sleep and when to prepare to wake up, shows a new study led by the University of Colorado Boulder and the Medical Research Council's Laboratory of Molecular Biology in Cambridge, England. Taken three hours before bedtime, this dose of caffeine induced a 40-minute phase delay in the roughly 24-hour human biological clock. Bright light had an even greater effect: bright light alone induced a circadian phase delay in the test subjects of about 85 minutes, and bright light combined with caffeine, 105 minutes. Three female and two male subjects were tested under four conditions for 49 days in a lab: low light and a placebo pill; low light and the equivalent of a 200mg caffeine pill; bright light and a placebo pill; and bright light and the caffeine pill. Saliva samples of each participant were tested periodically during the study for levels of the hormone melatonin, which increase to signal the onset of biological nighttime. The new results could benefit travellers, the researchers say. Properly timed caffeine use could help shift the circadian clocks of those flying west over multiple time zones.