A recent study has found that the average 16-year-old performs best in their exams  on just seven hours of sleep — far less than previously thought.

The scientists at Brigham Young University looked at how much sleep each individual got in relations to their test results in 1724 primary and high school students.

Published in the Eastern Economics Journal, researchers acknowledged that other socio-economic factors also played a part, such as how educated parents were, but that data indicated that sleep played an important role in test performance.

Eric Eide, study author, said: 'We're not talking about sleep deprivation. The data simply says that seven hours is optimal at that age.'

The findings showed that 10-year-olds need nine-and-a-half hours sleep while 12-year-olds need eight-and-a-half hours sleep for optimum performance in school assessments.

Most notably the team revealed that the optimum amount of sleep dropped for the older students.

Meanwhile, University of Chicago researchers found that lack of sleep can affect your testosterone levels which could impact on libido and energy levels overall.

The report which was published in the Journal of the American Medical association found that those that slept for less than five hours an evening more often than not, would have lowered testosterone levels shockingly similar to someone more than a decade younger.