UNITED STATES – A decade ago, high achievers would boast of how little sleep they got, as if it were a sign of courage and stamina.

That flipped on its head in recent years, with length and quality of sleep the new badge of honour.

Now, the most restful pastime humans can enjoy is starting to look like a competitive sport.

According to the burgeoning sleep-tech industry, if you want to win – and apparently you do want to win – you need a sleep coach and high-end gadgets.

To prove just how good you are at closing your eyes and nodding off, a metric is required. A nice, simple number that can proclaim whether you have been nailing or failing, and there are plenty of commercial and non-profit enterprises available to grade you.

The Washington-based National Sleep Foundation has even trademarked its Sleep Health Index, so you can be your Best Slept Self (also trademarked).

Among device-makers, Finland’s Oura Health Oy has a ring to be worn 24/7 that is claimed to be “like a sleep lab on your finger” and gives you a score out of 100.

Whoop, a wristband, tracks your sleep performance and charges each month to keep tabs.

Watches from Garmin, Samsung and Apple all provide a similar catalogue of data collated during the night to estimate phases such as deep, light and REM (rapid eye movement) sleep.

While increasingly accurate, these devices do not know which phase of sleep you are in – they use algorithms to make an educated guess.

How useful such devices are is contentious.

Many of the makers claim that customers experience improved sleep and health. Few offer peer-reviewed clinical data to back it up, however. Some psychologists and researchers dispute whether the data collected is accurate.

Even if it is accurate, there is still a problem: Most sleep-tracking devices merely collate information. They cannot directly improve sleep – that is up to you.

At best, a device connected to an app can offer recommendations based on the user’s habits coupled with clinical research. They are often generic: Sleep earlier, drink less alcohol and caffeine, exercise more, and cut screen time at night.

To be sure, it is possible that these devices offer a placebo effect and, if someone thinks he or she slept better, then that may be as good as actually sleeping better.

Yet in reality, there is little a person can do when he or she wakes up one morning feeling groggy and faced with a sleep score of 30 per cent – he or she is not likely to go back for another 90-minute nap. Arbitrary numbers and blanket advice are not particularly helpful, and are not likely to be followed.

Next up the sleep chain are coaches who offer practical, personalised and easy tips, with some visiting homes to provide guidance on mattress suitability, as well as assessing the light and sound in the bedroom.

Among the approaches offered to improve slumber is the R90 technique, which frames the night around 90-minute sleep cycles – the average time a person takes to go through the stages of light, deep and REM sleep. Courses are available online that may help.

Some companies want to climb into bed with you, or rather want you to climb into theirs.

Rest, a mail-order mattress-maker, tackles sleep with the notion that the right contours and firmness could make enough of a difference, with a mix of memory foam and air chambers that automatically adjust during the night. This might be a good solution for those who have a Goldilocks relationship with their bed, but may not help everyone.

Eight Sleep, a smart sleep-tech start-up based in the United States, sees it a little differently, and instead uses water tubing to dynamically cool or heat the bed. With two piezoelectric strips across its smart mattress, the company says it can capture heart rate, breathing rate and movement, while calculating heart-rate variability.

Temperature is known to be a component in phases of sleep, and it has also been established that it is easier to wake up from some stages of the sleep cycle than others.

A combination of vibrating motors and gradually adjusting the heat can be used to wake a person in the morning.

Despite all this practicality, Eight Sleep could not resist the gimmicky move of offering a sleep grade and telling you how often you got a perfect score. It even ran a social media campaign to play American cities off against one another. (Boston won.)

“You don’t improve what you don’t measure,” said co-founder and chief executive Matteo Franceschetti. “For most people, just having a proxy and a ballpark of how well they’re sleeping is very important.”

He is aware that the data collected by his mattresses and other gadgets are not perfect – although they are improving with better sensors and algorithms – but says this information is secondary anyway.

“The data is not the end point, it’s just the beginning,” said Mr Franceschetti. “Our goal is to improve your sleep, not to report how you slept.”

As sleep tech develops, this may be the most important thing for developers and consumers to keep in mind. Though there is no shortage of data available, and ways to tell you how badly you are failing, the products that will make a difference are those that can actually do something about it.

People live in the most over-coached era in history.

With an app or a Zoom call, there is a personal trainer on hand to help you with everything from your swim stroke to your golf swing, from marriage to parenting, from sleeping to living life itself. In many aspects, improvements can be measured.

If your golf handicap falls, your kid stops throwing peas at the wall and you have staved off divorce, then the results are pretty clear: That coach was probably a pretty good investment.

Sleep is more internal. Only you know if you slept well last night. Even if gadgets, sleep timing and apps can help you improve the duration and quality of sleep, it is not up to some algorithm to dictate whether you won or lost that evening’s sleep battle.

So if you are going to get yourself a sleep coach, find one that can deliver results, not just scores. BLOOMBERG