Join a loyalty scheme and you often get a reward or discount on your special day – but it may have strings attached

Celebrating your birthday isn’t just about getting presents and cards from family and friends. Signing up to loyalty schemes and newsletters can give you access to a host of freebies, deals and discounts from retailers to mark the big day.

With my birthday on the horizon I decided to look at what was on offer, and see which gifts came with some small print.

Gathering data used to be a fringe pursuit of Silicon Valley nerds. Now we’re all at it, recording everything from menstrual cycles and mobility to toothbrushing and time spent in daylight. Is this just narcissism redesigned for the big tech age?

I first heard about my friend Adam’s curious new habit in a busy pub. He said he’d been doing it for over a year, but had never spoken to anyone about it before. He had a furtive look around, then took out his phone and showed me the product of his burning obsession: a spreadsheet.

This was not a record of his annual tax return or numbers he was crunching for work (Adam is a data scientist). Instead, it was a spreadsheet recording the minutiae of his life, with dozens of columns tracking every element of his daily routine. It all started, he told me, because of a recurring argument with his boyfriend. His partner didn’t think they spent enough time together, but Adam thought that they did. There was only one way to settle this, he decided: cold, hard data. So he began keeping a note of the days they saw each other and the days they didn’t.