Everyone knows the afternoon slump... You get back from lunch and jump back into work, revived and sure that you will get the project finished up this afternoon. Then 3:00 rolls around, and you mentally just hit the wall. Can't sit at your desk - or if you do you will be spending a half hour watching cat videos on YouTube. Shouldn't hit the break room for the now-so-tempting carbs and sugar that beckon. Perhaps another cup of coffee will get you through to the end of the workday. ...you know, the afternoon slump.
Researchers looked at how the color (or wavelength) of lighting affects the afternoon slump. Participants were exposed to one of two lighting situations for 48 minutes in the afternoon: either blue light in the 470 nm wavelength or red light in the 630 nm wavelength.
While studies that look at light at night for keeping shift workers alert mainly focus on melatonin and blue light, this study was different in that it focused on the brainwave activity to determine alertness. The researchers measured the participants' brainwave activity using an electroencephalograph (EEG) to determine the alerting effects of the two lighting condition compared with just dim light.
The results showed that the red light was significantly more alerting in the afternoon. The researchers concluded: "Our results indicate that long-wavelength light is a more potent stimulus for modulating brain activities associated with daytime alertness than short-wavelength light."
Why is this study so interesting? First, there is a push towards using a lot of light in the blue spectrum during the day for its alerting effects. While the blue spectrum is needed in the morning to shut off melatonin production, it may be that our lighting needs shift over the course of the day.
Experiment for yourself. If you have a desk lamp, try a red lightbulb in it for a couple of hours after lunch. If it is winter time, you could try using a red heat bulb (in a clamp lamp so that you don't burn down the office) and get the added benefit of warm red light. See if red light can eliminate the dreaded 'afternoon slump' for you.