Runners are making do with a five-minute kip each hour as they pursue a world title, a Kiwi team member says.
Julia Chamberlain from Wanaka is taking part in the World Backyard Ultra Marathon championships in Otematata in the South Island's Waitaki District.
Sixty-two other countries are also taking part - each within their own backyard.
To fit in with the same start time for all the athletes around the world, the New Zealand team began their race at 1am on Sunday.
They have to run 6.7km every hour, which usually takes about 45-50 minutes, Chamberlain told Midday Report while she was competing another lap.
A lap can take 40 to 50 minutes and then runners grab tiny sleep breaks lasting anything from five minutes to 10 minutes.
"There's definitely a lack of sense occurring but everyone's in good spirits now we're back in daylight 'cos night-time was a bit grim."
Each team has 15 runners. Belgium, Hungary and New Zealand were the only teams with the full complement still going by late morning on Monday.
Chamberlain who is an experienced endurance athlete said each athlete has their own support crew to provide encouragement and tips.
Part of the appeal was seeing how far she could go, she said. It was a challenge to see how long she and the other runners could keep going.
It was difficult to predict how much longer she could continue but "hopefully a few more hours".
"I'm eating well - I'm pretty tired though."
The teams remain part of the race until they are down to one runner. It's expected that some will run 600-700km over that time.
The world record is 108 hours during which the runners completed over 700km.