TV review: Horizon: The Truth about Personality, BBC2 The Apprentice, BBC1

Michael Mosley, one of the more cheerful pop science presenters currently on screen, would like us to know that appearances can be deceptive. He might look happy, but he's not. "I get stressed and constantly fret about the future," he said at the beginning of Horizon: The Truth about Personality.

You know why that is, Michael, I thought. It's because you're bloody starving for at least two days a week. No wonder you're feeling a bit down. It was Michael Mosley, you might recall, who triggered the 5:2 fad with an earlier Horizon on the life-extending virtues of intermittent fasting. Last night, continuing Horizon's move into the territory of lab-certified self-help, he was searching for a quick-fix solution to anomie and wanhope. With the body under control (I assume he hasn't given up yet), he had turned to the mind and spirit.

Mosley's problem, he confessed, was Age-Related Pessimism. Though he was blithe as a child (and he had the home movies to prove it), he had become increasingly anxious as he grew older. Now he suffers from insomnia and a tendency to catastrophism, assuming that the worst will happen, if it can. Could this be measured objectively, though? And if he did discover that he was officially a gloomy guts, could he do anything about it? The answer to the first question was yes, though you hardly needed the neurological print-out to prove it: "I would suspect that I have a bias towards the negative," Mosley said as he was strapped into the wired shower cap for analysis. Which is, if you think about it, exactly what a pessimist would say.

The answer to the second question seemed to be a qualified yes. Mosley explored two relatively simple methods of retuning his outlook. The first was cognitive-bias modification, which consisted of spending 10 minutes a day picking a happy face out of a grid of random grouches. The other was meditation – 20 minutes of mindful tedium that he hoped would help break the circular nagging of his conscious mind.

And when he returned for testing it did seem as if something measurable had happened, his receptiveness to positive stimuli having noticeably improved and the magpie screeching of his right cerebral cortex having significantly calmed. His wife definitely thought it had helped, but then, given that she's an optimist, she would, wouldn't she? (Incidentally, the suggestion, addressed in passing, that some inherited characteristics can be passed on to your offspring, struck me as surely worth a Horizon all of its own. That's not just self-help, if it's true. That's an earthquake).

Every week, The Apprentice helpfully reminds us that optimism can be a pathology too. Last night was the interview episode, in which the remaining candidates get to play the part of the victim in an informational video about the horrors of workplace bullying. The awful thing being that they're so dim-wittedly full of themselves that you actually find yourself egging the bullies on. Jordan and Neil best exemplified the hazards of a rosy outlook on life, clinging to their utterly fantastical business plans even as they were dismantled in front of their eyes.

The women put up a better show, with Leah spitting out financial projections and spreadsheet details like some kind of entrepreneur-bot on tilt and Luisa earning the backhanded compliment that her idea was far better than the case she'd made for it. There's something chilling about Leah, who dreams of dedicating her medical training to the noble task of siphoning cash out of the pockets of the cosmetically anxious. "If you are tarring me with an unethical brush, you also need to tar every cosmetic surgeon working in the UK," she said indignantly when ethics were raised. No, Leah. We only have to tar the ones for whom profit is the sole motive. I'm thinking positive and assuming Luisa will win.

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