Aaron Taylor-Johnson needed "therapy" after finishing work on 'Nocturnal Animals'.
The 26-year-old actor - who picked up the Best Supporting Actor In A Motion Picture for his work as villain Ray Marcus in the thriller at Sunday (08.01.17) evening's Golden Globe awards - admitted his preparations for the role left him with sleepless nights, and he took around two or three months to fully shake off the dark role afterwards.
He told 'Entertainment Tonight': "I spent a lot of time watching documentaries on serial killers. It was not nice. It was sleepless nights, it was dark.
"Some actors do job to job. I do one thing a year. I need that time in order to remember and come back. To be grounded. A little bit of therapy in there. It was intense."
Despite his experiences, Aaron insisted he had "enjoyed every second" of working on the Tom Ford-directed thriller.
Accepting his award at the Beverly Hilton hotel, he said: "What a tremendous honour. Thank you, the Hollywood Foreign Press, for acknowledging me in this role. Tom Ford, thank you so much for this opportunity.
"Creating this role, collaborating on this journey was an immense joy. Thank you for raising the bar high. I enjoyed every second of it."
The British actor also thanked wife Sam Taylor-Johnson - who has daughters Angelica, 19, and Jessie, 11, with ex-husband Jay Jopling and Wylda, six, and Hero, four, with Aaron - for supporting him while he made the film because he wasn't "very pleasant" to live with.
He said: "I want to thank my wife for being there with me and supporting me through this. Thank you for putting up with me, Jesus. I was not very pleasant in this role.
"You're my soulmate and I love you very much. I'm blessed. I have four beautiful daughters... I have my parents watching tonight. Thank you."