Light and the Brain

by F.

I have a full-spectrum light I use in the winter to fend off depressed mood. It works like a charm. 20 minutes a day and I’m good to go. I soak up my daily 10,000 lux from my light starting around October and continuing until April or so. It sure seems to work, though the possibility that it’s a placebo can’t be ruled out.

But this post on the BPS blog summarizing some findings on the effect light has on the brain suggests something interesting is happening when the brain gets a big shot of lux-ious goodness:

Twenty minutes of bright white light delays sleepiness, and sends a stimulating wave through the brain, enhancing neural activity even during tasks that have nothing to do with vision.

Gilles Vandewalle and colleagues used an optic fibre to shine bright white light into either the left or right eye of 19 participants, and then left them to sit in the dark. For most of the participants, the light exposure delayed the onset of self-reported sleepiness. Brain imaging showed this sustained alertness was related to altered activity in the thalamus, a structure buried deep in the brain.

Brain imaging also showed the light enhanced the activity of brain regions engaged when the participants subsequently completed an auditory oddball task in the dark (i.e. listen out for odd tones that don’t match all the others). These regions included areas at the front and back of the brain known to be involved in paying attention.

Vandewalle, G., Balteau, E., Philips, C., Degueldre, C., Moreau, V., Sterpenich, V., Albouy, G., Darsaud, A., Desseilles, M., Dang-Vu, T.T., Peigneux, P., Luxen, A., Dijk, D-J. & Maquet, P. (2006). Daytime light exposure dynamically enhances brain responses. Current Biology, 16, 1616-1621.