In St Petersburg, a tall order to manage sleep and football

St Petersburg, Russia

THIS is one of the world's great cities, a magical mix of colours and canals that sparkle, especially in June, when the sun does not dip behind the Baltic Sea until around midnight.

Visitors and residents wander the streets and embankments through the small hours of what is night during the rest of the year but these days is just a brief dawn.

A favourite middle-of-the-night activity is strolling to the harbour, where thousands pack the banks of the Neva River to watch the bridges rise so boats can enter.

The nearly uninterrupted light this far north acts as a kind of human power plant, continuously fuelling millions of bodies but preventing them from getting the signals they need to begin the daily wind down that eventually leads to sleep.

These so-called White Nights make St Petersburg during the World Cup a truly captivating place to be but a potentially problematic location for players, especially those whose teams are based here.

The tension of the competition robs them of rest, and shouldering the weight of the country they represent can be nerve-racking.

Factor in the almost never-ending light, and the result is an under-rested team whose players' bodies have no idea what time it is when kickoff arrives.

"It's strange, but it's nice," said Bryan Ruiz, the Costa Rica captain, whose team is spending the tournament at a hotel here. "We have to close the curtains around 10:30pm or 11pm. Otherwise, we cannot sleep."

The temptation to get up and leave the hotel is strong, he added.

The body operates on a 24-hour clock, and the ability to set and reset that clock depends on a light-dark cycle, explained Steven Lockley, a Harvard neuroscientist with Brigham and Women's Hospital's Division of Sleep and Circadian Disorders.

Remove darkness from that cycle, and sleep and athletic performance can be thrown out of whack. He said: "All things being equal, I would have chosen to stay farther south."

St Petersburg is the northernmost location for World Cup competition since 1958, when two matches took place in Sandviken, Sweden, which is less than 1 degree of latitude north of St Petersburg (60.37 versus 59.56, for geography buffs).

It represents the polar opposite of the 2010 (South Africa) and 2014 (Brazil) tournaments, which took place during winter in the Southern Hemisphere. Darkness generally descended by 6 p.m.

Mr Lockley has consulted on sleep and light strategies for Nasa, for teams in the National Football League and the National Basketball Association in the US, and with race car drivers, all of whom regularly travel to different environments and time zones.

He said that any player who competed or slept in St Petersburg would be well advised to start reducing exposure to light long before bedtime.

Light acts as a stimulant, similar to the way caffeine does, even in people who are blind. The human eye contains a protein that detects light called melanopsin, which is different from the rods and cones people use to see, Mr Lockley explained.

Its stimulating effects linger long after the lights go off. "The more light you are exposed to, the more alert you are, the longer it takes to go to sleep and the less deep sleep you experience," he said.

St Petersburg and its environs are playing host to seven matches and five teams during the tournament: Costa Rica, England, Croatia, Saudi Arabia and South Korea.

Saudi Arabia lost its first two matches, and so did South Korea. Saudi Arabia's World Cup campaign ended after its third and final group match on Monday against Egypt, although the team's problems on the field probably had more to do with not being very good at football than not getting enough rest. The same goes for South Korea.

Andy Walker, a spokesman for England's Football Association, said team officials took special care to address the sleep issue in the months leading up to the competition.

The team is staying at the ForRestMix club in Repino, a village about 40km northwest of St Petersburg. "We had the hotel install the extra thick curtains, made of special material," Mr Walker said.

The team also brought in special mattresses to maximise player comfort. The training staff also has plenty of eye shades available should players need them.

England beat Tunisia 2-1 in its first match, though it did fail to convert a slew of easy goal opportunities. No problems there against Panama on Sunday when England won 6-1.

Tomislav Pacak, a spokesman for Croatia's team, said the federation had arranged ahead of time for extra dark and thick curtains at the Forest Rhapsody Resort, north of St Petersburg. These have been "working perfectly fine", he said.

Croatia beat Nigeria in its first match and last Thursday defeated Argentina 3-0 in a match played some 1,100km southeast in Nizhny Novgorod.

South Korea lost its first match against Sweden and later to Mexico. Costa Rica lost its first match to Serbia and then lost to Brazil. Tally it up and the St Petersburg teams are 4-6 (four wins, six losses) in the tournament so far.

And while St Petersburg's White Nights cannot be cited as the primary factor in defeats in a tournament in which results shift on tiny margins unrelated to sleep, any slight advantage or disadvantage can make a difference.

"It's a shame that teams can take the negative impact of lack of sleep for granted," Mr Lockley said. "This is biology. It affects everyone." NYTIMES