Two small to medium-sized businesses (SMB) in the south of France say they have seen benefits from switching to a four-day working week. "We have less stress, they are very motivated, they are more efficient," says Nicolas Michel, head of the IT company Pro Sima. However, there are some unknowns around the rhythm's long-term effects. Nathalie Commeiras, a professor at the University of Montpellier, says employees are "likely to be more exhausted" with "overload of work". IMAGES AND SOUNDBITES