According to Phuket police, Jonathan Mark Lemley, 28, rode a motorcycle around the Karon Circle and nearby roads about 5.30am in a swirling pattern, sometimes attempting to stand the bike on one wheel.
It could have been quite noisy.
Police believe he may have been knocked senseless for keeping people awake early on Saturday morning or have possibly been assaulted by hoodlums who may have felt he was daring people to react, or invading their space.
There is no evidence linking Mr Lemley's injuries to any of the theories at this stage.
The American, who arrived on Phuket on a tourist entry permit on October 20, remains in a coma at Vachira Phuket Hospital's intensive care unit. He is now in a stable condition.
Police are hoping that he will soon recover consciousness and be able to tell them what happened.
In many incidents involving head injuries to motorcyclists in the past, the riders often have no recollection of what transpired. It can take months, if ever, before memories return.
Officers from Karon Police Station say that they have so far found no camera footage explaining how Mr Lemley ended up on the beach at Karon, unconscious with serious head wounds.
He was found about 8am that morning, not far from Karon's landmark lagoon.
There was no identification on him and his head was bleeding.
On the sand not far away was a black Honda motorcycle with a Malaysian numberplate.
Mr Lemley's wife is believed to have also come to Phuket.
*Hooning is a term used primarily in Australia and New Zealand to describe riders or drivers who indulge in speeding, burnouts, doughnuts or screeching tyres.