In late October 2009, Stephen Fry quit Twitter after someone called him boring. In late October this year he did it again, this time taking umbrage with journalists. Fry's actions, as well as providing a reliable way to tell when the clocks have gone back, highlight a topic of scientific inquiry that we do not discuss enough: human brain chemistry.
Fry has publicly related his struggles with bipolar disorder. His efforts to raise awareness of mental health problems, and diminish the stigma associated with them, deserve much praise. That Fry's tolerance of criticism or unflattering media portrayal appears to be adversely affected by reductions in daytime light levels puts him among 10 per cent of the world's population.
Seasonal affective disorder is just a part of it, though - mental illness as a whole is even more common. The United States has the highest prevalence (26.4 per cent), but it seems that China is catching up: a 2009 survey put the incidence at 17.5 per cent. The Chinese government, normally so allergic to anything with a negative connotation, is tackling this head-on. After a string of suicides among stressed and depressed political workers, the Communist Party has decided there will now be psychological tests for those applying for top jobs in the Chinese government. Wider availability of medication will also help.
Antidepressants are the most widely prescribed class of drugs in the US for a reason: they can work wonders by adjusting the amount of neurotransmitter serotonin in the brain. The effect is in part due to a synergy between serotonin and chemicals associated with the placebo effect. Details aside, this branch of chemistry can make the difference between a functioning or a non-functioning human being.
For reasons no one has yet worked out, light affects serotonin levels, too. That's why the singer Katy Perry recently announced that she and her new husband, Russell Brand, won't be moving to Britain: she is a "serotonin girl", she says, and sunny California keeps her happy. University of Vienna researchers have shown that in brains such as Perry's, molecules that remove serotonin from brain cells become twice as active in low light conditions. That's why light therapy works to stave off the mild depression known as the winter blues.
Treating depression, rather than ignoring it, will make your world a better place. In September, a Cambridge University study showed that raising serotonin levels makes people more tolerant of poor behaviour in those around them, and less inclined to inflict punishment or harm - even if that harm would ultimately be for the common good. Which, given the Chinese finding that politicians have a tendency to depression, makes one glad the Spending Review wasn't left until after the clocks went back.