THE relentless pursuit of marginal gains has led Oxford United to embark on a new frontier – sleep.

In the first research of its kind in English football, four players have started wearing rings at night which connect to their smart phones.

It keeps track of the quantity and quality of their sleep, which can then be cross-referenced by the sports science department with the GPS data from training sessions.

The project began a few weeks ago, just before United embarked on a gruelling February which sees them squeeze nine games into 29 days.

“The only two natural forms of recovery are sleep and sun,” said head coach Karl Robinson.

“We can’t guarantee the sun, so sleep is huge.”

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It is part of the U’s attempts to lead the way in the mental and emotional aspects of players’ lives.

That includes being the first to have a sports psychotherapist embedded in the club.

Gary Bloom, who chaired a conference at the Kassam Stadium this week showcasing United’s efforts, believes sleep is a vital area of research and although it is early days, they are yielding some interesting results.

He said: “Our belief is if players are not getting full rest they are particularly susceptible to injury.

“The most interesting aspect is the biggest problem sleeping was on the rest days.

“We thought that sleep post-match would be the most obvious problem.”

One theory is if players go from a game to total rest the following day, it could cause problems sleeping because their bodies are used to burning a large amount of energy.

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Another area United want to tackle with the research is the use of artificial supplements which are widespread in the game.

Robinson said: “We’re not an advocate of sleeping tablets.

“We know they exist within the game but I don’t think it’s healthy.

“I know people do it to get that instant sleep, but we believe in natural sleep here.”

Bloom says two of the ring-wearers have reported progress in their rest after looking at ‘sleep hygiene’.

Improvements can be made by avoiding electronic devices before bed, the temperature of the room and evening meal times.

Young children can also be a factor.

Robinson said: “In an ideal world – and I know the partners won’t be overly happy to hear this – we would prefer the players to sleep in a room on their own after games.”

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Such intrusion into personal lives restricts the research to volunteers, who have to buy the technology themselves to prove it has not been forced on them.

Bloom said: “I think (in the future) it will be vital as players tool up to be the most effective version of themselves, but there’s a whole issue of monitoring players’ personal habits.

“Could a club tell players it is mandatory to wear these devices and what would happen if a player said I don’t want you to know?

“That is a confidentiality issue which is ethically quite a tricky area.”