The longer we work in a given time period, the more our productivity for every additional hour worked - our marginal productivity - declines.

The service costs $8.95 a month for the first four hours of use and $2.95 for each additional hour thereafter.

The trial was judged to have been a failure, presumably because people had not received the usual additional hour in summer to which they had become accustomed.

Researchers also found that sleeping beyond the recommended seven to eight hours was linked to a 20 per cent increased risk of the disease per additional hour slept.

An additional hour of music was recorded during the recording sessions of this album.