The good news for chocoholics is that their favourite snack works wonders thanks to cocoa flavanols, a natural compound found to protect cognitive functions including memory and mental processing.
It may not be such good news for waistlines as researchers reckon the longer that chocolate is part of a daily diet, the better it is for the brainâ€™s performance.
But it is good for workers, including those who have to come into the office after a night without sleep, said the team from Italyâ€™s University of Lâ€™Aguila for the journal Frontiers In Nutrition.
For the flavanols cancel out the effects of sleep deprivaiton on the brain – normally tiredness would lead to lapses in concentration and less accuracy when performing tasks, for instance.
Researchers at the universityâ€™s department of biotechnological and applied clinical sciences, studied existing papers, reports and published data on the effects of cocoa.
They found the evidence points to what is called â€˜neuroprotectiveâ€™ qualities of the flavanols for a few hours after eating a cocoa-derived product, such as chocolate, and for longer if eaten regularly.
The findings were hailed as â€˜promisingâ€™ for people that suffer from chronic sleep deprivation or work shifts and for older people who suffer from a slowdown in cognitive abilities.
For younger and healthier adults, the effects of cocoa flavanols kick in with the more complex tasks, said the study.
But older people, who are more likely to suffer from memory decline or other â€˜cognitive impairmentsâ€™ will feel a greater benefit as it helps concentration, working memory and other functions.
Co-researcher Michele Ferrara said: â€œThis result suggests the potential of cocoa flavanols to protect cognition in vulnerable populations over time by improving cognitive performance.â€
The flavanols also improve the heart and cardiovascular health which, in turn, increases the volume of blood flow to areas of the brain – the dentate gyrus of the hippocampus – normally affected by the ageing process.
Ferrara added: â€œThis structure is particularly affected by aging and therefore the potential source of age-related memory decline in humans.
â€œRegular intake of cocoa and chocolate could indeed provide beneficial effects on cognitive functioning over time.â€
But before reaching for the digestives or bars of top selling choc, the researchers recommend dark chocolate as it has more flavanols and less sugar and milk which are more calorific.
The report concludes: â€œDark chocolate is a rich source of flavanols. So we always eat some dark chocolate. Every day.â€
The researchers looked at nearly 50 published studies, experiments and randomised trials which involved human consumption of cocoa over periods from a few hours to every day for three months.