Taking a “nana nap” in the middle of the day has been proved more beneficial than a cup of coffee for concentration and efficiency.

Researchers at the University of California San Diego found memory test results proved the same benefit applies if you have a 90-minute daytime nap to a full night’s sleep.

But they found a double espresso works less well than a 20-minute nap.

The study also found older adults on average performed better on a simple memory test if they got more sleep, while in younger adults aged 27 years on average the quality of sleep also affected how they performed on the same test.

Source: FoodWeek Online, 23 February 2010, http://www.foodweek.com.au/Default.aspx?tabid=53&ID=6609