Some interesting scientific info on blue light, melatonin production and the physiology of the human eye. According to this article (see below), it takes 90 minutes after turning off the blue light for your body to start producing melatonin. Maybe a good rule of thumb would be no computer after dinner? Geez. Maybe F.lux is the answer? Maybe a pair of wavelength-changing after-dinner computer-reading glasses?

http://www.nytimes.com/2011/07/05/he...pagewanted=all