SINGAPORE - A full-time national serviceman (NSF) who apparently had not slept for at least 24 hours was behind the wheel of a five-seater Subaru Forrester SUV when it veered to the right and smashed head-on into a tree along Changi Coast Road, a coroner' s court heard.

NSF Yukio Matsuo, 21, was pronounced dead at the scene at 7.23am on July 29, 2016, after he was extricated from the severely damaged vehicle.

His five passengers, all regulars from Singapore Navy, were asleep at the time of impact and suffered injuries of varying severity.

At an inquest into Mr Matsuo's death on Wednesday (Sept 20), the court heard that he had played games, mahjong and chatted with his navy mates at Aloha chalet before heading for breakfast at around 5am.

Mr Matsuo had told his father that he would not be returning home after his day of work at Changi Naval Base. He said he would be attending a gathering at a chalet, and would be reporting back to his camp directly from the chalet.

State Coroner Marvin Bay said that Mr Matsuo had stayed up the entire night after work to chat, play cards and mahjong with his fellow Navy servicemen.

He said fatigue from inadequate rest likely compromised his ability to operate his car safely. The car had veered to the right while travelling on a straight road, and hit the tree.

Given that all five passengers had engaged in the same activities the night before, had fallen asleep and were oblivious about the cause of the crash, it would be reasonable to expect that Mr Matsuo might be similarly fatigued from inadequate rest, he said.

Finding his death to be an "unfortunate traffic misadventure", the coroner said this case amply demonstrates the profound dangers of driving while sleep-deprived.

The sad circumstances of Mr Matsuo's demise are a stark lesson of the catastrophic consequences that can ensue from sleep deprivation to the driver, as well as his passengers, he added.