Science Questions

Do daylight replacement boxes work?

After a week of lethargy as the daylight gets dimmer and shorter (which seems worse this year because we hardly had a summer worth speaking of) I've been contemplating getting a light box. Is there any research on this and do they actually work? Georgina Allen

There’s lots of research on light boxes that really do work.  Lots of people have Seasonal Affective Disorder.  It’s a real entity, we think it has a genetic basis.  This is where people feel the urge to want to hibernate as soon as you go into Winter.  As soon as the days start to get shorter, you don’t get enough sun exposure.  Or if you have to work nights, it can make you feel really quite nasty and quite depressed.  For people who have this it can be quite disabling.  So scientists have found that if you get a light box which gives you lots and lots of light in the morning (morning seems to be quite important) it seems to make people feel better.  

What’s the physiological basis for it?  Well, you have a body clock in the part of the brain called the suprachiasmatic nucleus in the hypothalamus.  It’s got about five thousand nerve cells that work like a genetic domino effect.  One gene turns on a second gene which turns on a third gene and that turns on a fourth gene and that turns off the first gene again and the whole thing goes round in a circle.  That’s how it keeps time.  It needs to be able to reset itself because if you go abroad on an aeroplane you get jetlagged for a little while before it resets.  Recently, in the last four or five years, scientists have found there’s a population of nerve cells in your eyes which see light which is at the blue end of the spectrum and they don’t actually show your brain what they’re seeing.  They just tell your body clock what they’re seeing.  They tell the body clock when it’s bright and when it’s dark and by doing that they can reset your body clock and keep it in time.  By shining this extra light, scientists think that’s how you can rescue your body clock if you need to.

October 2007