I took a quick cultural divertion to the Louvre yesterday, on my way to visit the EDF Trading team in Paris. Some of the team work nights, so we covered a lot about body clocks and Zeitgebers. It was a lovely bright office, which helped us all stay awake!
Sunlight is a powerful stimulus for improving mood and concentration - especially when you've had an early start and you need a pick-me-up in the afternoon.