Light Therapy and Haemoglobin

Just a quick note this time – this one’s a fairly old article, and from a quick look at this researcher’s work it looks like he may no longer be pursuing this exact line.

Light therapy for Seasonal Affective Disorder is normally associated with absorbing bright light through the eyes. This article seems to at least hint at light transmission into the skin – for skin is far from completely opaque, as anyone who’s tried to make a realistic skin texture in 3d computer graphics can testify – having an affect on winter blues. The haemoglobin in our blood is light sensitive, and can act as a messenger to our brain, according to Dan Oren of Yale University.

It makes me think of pictures I’ve seen of brave or masochistic russians sunbathing in moments of midwinter sunshine – perhaps there’s more to it than bloody mindedness.

Sad Fat Rats

Or “We are not alone”

Rats and mice are valuable experimental animals, as they share so much biologically with us – but they’re not particularly good subjects for studying Seasonal Affective Depression. Mice are nocturnal, and do most of their running around at times when their melatonin levels are high – when we’re safely asleep. Accordingly, two researchers, Prof. Noga Kronfeld-Schor of Tel Aviv University and, Prof. Haim Einat of the University of Minnesota decided to look at using a diurnal experimental subject, the Fat Sand Rat (Psammomys obesus) a relative of the gerbil native to the middle east and north africa.Sad Fat Rat

They found the rats would develop symptoms matching Winter Blues when given simulated shorter winter , and better yet would, respond to light therapy in a way simular to human sufferers. This doesn’t mean we’re any closer to effective treatments, but it is good to have an animal subject which behaves analogously to humans.

One important point to take away is that this helps us eliminate the possibility of light therapy’s efficacy being due to the placebo effect, as the sand rats are unlikely to have been able to divine the researcher’s intentions. There is, of course, the possibility that the sand rats are just depressed because people keep calling them fat.

Tal Ashkenazy, Haim Einat, Noga Kronfeld-Schor. We are in the dark here: induction of depression- and anxiety-like behaviours in the diurnal fat sand rat, by short daylight or melatonin injections. The International Journal of Neuropsychopharmacology, 2008; 12 (01): 83 DOI: 10.1017/S1461145708009115

Let’s start with a digression or “The nucleus must be conserved!”

When I was a kid I loved to watch Doctor Who (For that matter, I still love it, but I’m not terrified of it anymore) and follow The Doctor on his travels through the universe, encountering robots, aliens, time travellers and an endless sucession of alien planets that look like the same disused gravel quarry.

The Ark in Space

In one of these, The Ark in Space we meet a particularly nasty insectoid hive-mind which is gobbling up the sleeping crew of a long haul spaceship, one by one. As each crew member is posessed by the aliens, they say “Contact has been made”, to which the already-posessed crewmember who has awoken them replies “The nucleus must be conserved”.

Now, the suprachiasmatic nucleus is a little blob around the size of a pea, hidden somewhere deep in our brains. Among its task is the regulation of our bodily clocks. When we’re exposed to light, the suprachiasmatic nucleus acts to suppress the production of melatonin. When there’s not enough light, melatonin production is not controlled properly, and gloomy sluggish slothful winter blues result. Or that’s one theory of many, anyway. More on that later, but for the moment I just wanted to meditate on how every time I hear the phrase “suprachiasmatic nucleus” I see a giant alien insect saying “The nucleus must be conserved!”.

As indeed it must.