I sleep too much – so I flew across the world to try and find out why

There are medical risks to not getting enough sleep over a sustained period, including an increase in the likelihood of developing heart disease, diabetes and high blood pressure, as well as depression and anxiety. But there are downsides to excessive sleeping too. For one, it’s a terrible waste of time.

I’m achingly jealous of minimal sleepers. People like Margaret Thatcher, who famously required four hours. Tom Ford and Donald Trump claim to need only three. That’s seven more waking hours than I have each day, or 49 bonus hours a week. Enough time to read 255 extra books a year, to run 500 marathons (I’m a slow runner) or, more likely in my case, to rewatch the entire box set of Succession 63 times over.

Some rather obvious tips to combat tiredness are listed on the NHS website. Things like exercising regularly, losing weight, and drinking more water and less alcohol. I’ve tried them all: bouts of training for half-marathons, boxing sessions, then fallow periods of no exercise at all; I’ve lost weight and I’ve gained weight and I’ve gone virtually teetotal; I’ve mainlined carbs and followed protein-rich meal plans, but nothing touched my baseline, the minimum sleep I require.

And so for years I concluded I’m just a sleepy – read lazy – person.

Brad Johnson is anything but a lazy person. As a boy he would wake early and, while others slept, read or play basketball or listen to sport on the radio.

He is 67 now, the retired chief financial officer of an outdoor-equipment retailer, living in Utah with his wife Rosie. To this day he sleeps for about five hours a night. He doesn’t use an alarm clock. ‘If you offered me $1 million to sleep six-plus hours this evening,’ he tells me, ‘I could not do it.’

In all, six members of his extended family displayed similar patterns. They didn’t appear to struggle with alertness as a result of a lack of sleep. Their bodies just needed less of it.

When he was 48, researchers from the University of Utah performed blood tests on Brad and his relatives, and discovered that the cause was genetic. They are naturally ‘short sleepers’.

Their case is rare – the particular gene mutation found in the Johnson family shows up in just one in every 25,000 people. But there are other gene mutations that have a similar effect.

Scientists at the University of California, San Francisco, heard from a woman who woke up at four o’clock every morning, completely alert, despite having had only four hours of sleep, and went on to research this further. In 2009, they discovered a mutation in the gene DEC2, which helps control the levels of orexin in the body, a hormone involved in regulating, among other things, wakefulness.

Tests on mice engineered to have the same DEC2 mutation showed not only less sleep time but, crucially, increased vigilance time compared with control mice without the mutation. Put simply, a lack of sleep in those with the gene mutation didn’t affect alertness.

In all, it is estimated that between one and three per cent of people are naturally short sleepers. In other words, masses of people are simply born this way.