The US Open's night sessions are legendary. The atmosphere really ramps up after the sun goes down in Flushing Meadows and a couple of the game's biggest stars face each other across the net in one of the big tennis arenas.

However, some matches end so late that by the time they do, there are hardly any spectators left in the stands. The athletes also suffer. Only a few hundred fans saw the match point when Zheng Qinwen of China and Croatia's Donna Vekic faced each other in a rematch of the Olympic gold-medal contest. The match ended at 2:15 a.m. local time, setting a new record for the latest women's match at the US Open.

The third-round match between Germany's Alexander Zverev and Tomas Martin Etcheverry of Argentina ended after 2:30 am. It was the second-latest finish in US Open history. In 2022, the duel between Carlos Alcaraz and Jannik Sinner lasted until 2:50 a.m.

'A total mess'

"The tennis scheduling situation is a total mess," Andy Murray complained on X, the social media platform formerly known as Twitter.

Due to the ongoing debate about the wisdom of playing so late, US Open organizers introduced a new rule for this year's tournament, which stipulates that if a match has not started by 11.15 p.m. due to an ongoing previous match, it should be moved to another court. After all, four arenas are available: the Arthur Ashe Stadium (around 24,000 seats), the Louis Armstrong Stadium (14,000), the Grandstand (more than 8,000) and Court 17 (2,800).

"I think that is a really good start," Coco Gauff told reporters in her pre-tournament press conference. 

The winner of the 2023 US Open women's singles title has long been a vocal critic of late starts.

"I definitely think it's not healthy and maybe not fair for those who have to play late because it does ruin your schedule," she said during this summer's French Open.

Loss of sleep = loss of performance

In fact, competitive sport at night is not healthy – at least in the long term. And even if you only have to hit the court once at night, you are at a disadvantage if you face a well-rested opponent in your next match, whose previous match finished earlier.

According to a 2019 study by Ruhr University in Bochum on the importance of sleep in competitive sport, sleep loss leads to slower and less accurate cognitive performance. Concentration, reaction time, memory and decision-making were worse in tests with adult subjects who had slept for less than seven hours.

"Sleep determines cognitive and motor performance," Dr. Utz Niklas Walter said in an interview with the "Sportärztezeitung," a sports doctors' periodical.

"The more restful the night's sleep, the more likely it is that the body will perform at its best and adapt positively," he said.

"There should be about two hours between intensive sporting activity and going to bed. This time should also be used to think about things other than competitive sport."

'Physical and mental fatigue'

According to the Professional Tennis Players Association (PTPA), the number of night matches at the Grand Slam tournaments in Melbourne, Paris and New York has doubled since 2018. The other Grand Slam, Wimbledon, generally does not organize night sessions because the stadiums are located in a residential area of London.

 According to the PTPA, the risk of a player getting injured is 25% higher during a late match.

"There needs to be a greater focus on players' health," PTPA Deputy Executive Director Romain Rosenberg told the DPA news agency.

"It's no wonder that players pull out of tournaments, are broken and injured. The physical and mental fatigue is real."

Zverev also experienced such a moment after a night match at this US Open. In the round of 16 against Brandon Nakashima of the United States, a day-and-half after his victory against Etcheverry, the German twisted his ankle in the fourth set and limped slightly for a while.

'Not much the tournament can do'

Zverev declined to blame the tournament organizers for the late scheduling of the matches.

"Maybe the night sessions could be started earlier," said the 2021 Olympic champion who happens to hold the record for the latest tennis match in history.

His February 2022 match against Jenson Brooksby at the ATP tournament in Acapulco ended at 4:55 a.m. local time. In his next match, he was disqualified after a throwing a temper tantrum. Could this have been at least in part due to a lack of sleep?

"There's not much that the tournament can do," Zverev said referring to his late match at this year's US Open. "There's nothing to blame them for."

In the hands of the organizers

However, the fact of the matter is that it is the organizers who make the schedule, and if they wanted to they, as a Wimbledon, could simply lose the night sessions.

Or they could set at cutoff point of 1:00 a.m., for example, after which a given match would have to be resumed on the next day – after the players have been given sufficient time to get a good night's sleep.

This article was originally published in German.