Almost everyone struggles with getting stuff done. But some of us struggle with the stage before that: just figuring out what it is we need to do. The to-do list is, in theory, the answer. It’s a time-honoured system that’s beautiful in its simplicity: work out what needs to be done and in what order, write down the tasks, do them, and then, one-by-one, cross them out.

Psychologist and author Dr David Cohen believes his struggle to stay organised is helped, but not entirely solved, by his to-do lists, which must be on paper – preferably in a diary – and need to be constantly monitored. “My family think I’m chaotic,” he says, “but I would be much more so without my lists – they’ve kept me in line for years.”

Cohen puts our love of to-do lists down to three reasons: they dampen anxiety about the chaos of life; they give us a structure, a plan that we can stick to; and they are proof of what we have achieved that day, week or month.

A system is needed – and scribbled notes on hands won’t cut it.

In less harried days, our memories might have done the work. Russian psychologist Bluma Zeigarnik was perhaps the first to note the brain’s obsession with pressing tasks. The so-called “Zeigarnik effect” – that we remember things we need to do better than things we’ve done – stemmed from observing that waiters could only recall diners’ orders before they had been served. After the dishes had been delivered, their memories simply erased who’d had the steak and who’d had the soup. The deed was done and the brain was ready to let go.

More recently, a study by professors Baumeister and Masicampo from Wake Forest University showed that, while tasks we haven’t done distract us, just making a plan to get them done can free us from this anxiety. The pair observed that people underperform on a task when they are unable to finish a warm-up activity that would usually precede it. However, when participants were allowed to make and note down concrete plans to finish the warm-up activity, performance on the next task substantially improved. As Bechman notes: “Simply writing the tasks down will make you more effective.”

Some people resist this kind of structure, however. They think it will stymie their creativity or prevent them from being flexible with their working day. For time management expert David Allen – whose book Getting Things Done: The Art of Stress-Free Productivity has made him a cult figure in the field –these free-spirited types are plain wrong. He believes anyone with a full schedule and no structure will struggle to cope. A system is needed – and scribbled notes on hands won’t cut it.

“Write my novel” is a pretty foreboding task; “outline first chapter of my novel” is far friendlier

It’s not enough to scrawl “bank” or “Mum” on a Post-it note, says Allen – you need more detail. Is it an email, a visit or a phone call, and for what purpose? If your to-do list isn’t clear and to the point, your tasks probably won’t get done – and they certainly won’t be prioritised.

Detail isn’t the only important factor, however: you also need to be realistic about how long things will take if you want to construct a workable timetable for the day. That means factoring in the potential for floating off onto social media or other distractions if you know you’re susceptible.

One trap people fall into is to consistently avoid tackling the larger, more major projects. The best way to overcome this is to break them down into much smaller, achievable blocks. “Write my novel” is a pretty foreboding task; “outline first chapter of my novel” is far friendlier and stands a chance of getting done.

Does Cohen finish everything on his lists? “Oh God no! I found an old diary the other day from six years ago, and there was something in there that I still haven’t done.” On the other hand, he has written 35 books – on subjects ranging from body language to Sigmund Freud’s cocaine use – so his to-do lists are yielding pretty impressive results.