Transport for London says it is investigating the footage
Investigators are looking at footage showing a tram driver with his eyes closed at the controls on the same track as the fatal Croydon crash.
The driver is seen with his eyes closed as the tram travels between Coombe Lane and Gravel Hill, having already travelled through a bend near Sandilands station.
It was on this section of track that a tram derailed on November 9, killing seven people and injuring more than 50.
A passenger, who filmed the incident, said he was "incredulous" after spotting the driver struggling to remain upright
in his seat.
"It was the most surreal thing because the tram is zooming along and the driver seems to be falling asleep," he told The Sun.
"It seemed like he had perfected the art and knew when the next stop was approaching to wake up.
"He reminded me of someone who dozes off in a meeting - except if you doze off in a meeting you are not killing anyone."
It has been estimated that the tram was travelling at more than 40mph at the time the footage was filmed at 6pm on 14 April.
The passenger added: "If you are in charge of 50 plus lives and you are that exhausted its quite a dangerous thing. He would nod off and then jolt back up near the stops.
"Perhaps he'd had a really long day. It's a downhill stretch and it felt to me like the tram was going too fast."
Transport for London says it is investigating the footage.
A spokesperson said: "(We) have asked First Group, who operate the tram network, to take all necessary action and report back to us as soon as possible."
A FirstGroup spokesperson added: "We have not seen this video before and it will now be subject to a full investigation.
"If the situation is as it appears then this is completely unacceptable and appropriate action will be taken."