The driver of a train which crashed into buffers at King's Cross was suffering from fatigue, according to an accident investigation.
The driver was coming to the end of a night shift when the crash happened early on August 15.
Four passengers and one member of staff reported minor injuries in the 4mph crash. The impact pushed the buffers back by over a metre.
The four-carriage train involved was the 5.13am Great Northern service from Royston, Hertfordshire.
The driver, who was not identified by the Rail Accident Investigation Branch, "briefly closed her eyes because they felt tired" in the seconds before the collision.
When she opened them she hit the emergency brake but it was too late to avoid hitting the buffers.
The RAIB revealed that it was her first night shift after a period of rest days and she was "not sufficiently well rested".
She had two years' experience of driving trains on the lines out of London King's Cross.
Speaking on the day of the crash, passenger Natasha Coella, 36, said: