Bill Harvey: Light in the black

Melatonin is an interesting hormone.

Secreted by the pineal gland, the neurohormone is found in higher serum concentrations during the hours of darkness and when levels of the neurotransmitter dopamine are reduced. The opposite is the case during daylight hours and it seems that this balance is an underlying driver for the circadian rhythms that govern our metabolic processes. Those that are so easily disrupted by modern life – jet lag, poor health linked to odd working patterns under constant artificial light, seasonal affective disorder are all in various ways linked.

Some time ago I was lucky enough to interview Professor Russell Foster who had first noticed how cortically blind mice were still able to exhibit signs of diurnal behaviour patterns. When he first postulated an additional retinal photoreceptor to rods and cones, he was dismissed offhand by colleagues.