Joely Richardson went into "autopilot" after her sister Natasha Richardson died.
The British actress - who lost her beloved sibling earlier this year after a skiing accident in Quebec, Canada - threw herself into her work to help her cope with Natasha's passing but found it difficult because of some uncanny resemblances between her personal life and career.
She explained: "A strange autopilot kicks in. Your psyche puts your work day into a different compartment from your private life. I'm not kidding - my first shot back on set was reacting to someone dying."
The 44-year-old actress found Natasha's death a massive shock because she had never considered life without her.
She told Tatler magazine: "We were such opposites, but completely enmeshed in each other. I hadn't lived a day in my life without her. You worry about your children and your elders, but I never imagined such a thing as this. Tash was a given to me.
"The shock shatters you on a cellular level, and it takes time for the pieces to come back together, albeit in a different formation.
"So much of what I am is who Tasha was, and, I think, sharing all those formative years, there is level of merging... I cannot imagine that there will ever be a day when I don't think of Tasha."
Natasha is survived by her actor husband Liam Neeson and their two sons, Michael, 14, and 13-year-old Daniel.