Taking an afternoon nap at the desk dramatically improves workers’performance, according to research by Nasa.

　　Bosses should welcome the sight of staff slumped over their keyboards because when they wake up their performance will increase by 35 per cent and their ability to judge the right business decisions by 50 per cent, the space research agency claims.

　　However, they should sleep for only 45 minutes. Any longer and they risk fallingsintosa deep sleep and will wake up groggy.

　　The research was aimed originally at predicting the performance of astronauts on long missions. However, the scientist behind the study said that the same results had been achieved by office workers performing less glamorous tasks.

　　Mark Rosekind, chief scientist of California-based Alertness Solutions, said that many managers believed it was an admission of weakness to give in to tiredness.“It is a false myth that if you spend more hours awake you are more productive,”he said.

　　Most people suffer a decline in their alertness between 3pm and 5pm, when they would most benefit from taking a nap. Mr Rosekind said that napping was especially important in safety-critical jobs, such as piloting passenger jets on long-haul flights.“Controlled rest on the flight deck improves alertness in the final critical phase,”he said.

　　Maximum alertness was normally achieved from 9-11am and 9-11pm, Mr Rosekind said.