Russian-born Kasatkina, who switched nationality in March, shut her season down in October citing the mental strain of a heavy tour schedule and emotional stress from her battle to gain full Australian competition eligibility.
"For us tennis players, it is very difficult to accept that you need a break," she told Australian Associated Press on Tuesday.
"We have tournament after tournament and we have to defend the points from the previous season which is an additional anxiety. I just felt that if I pushed for longer I would have got in a deeper hole."
Kasatkina, who has not returned to Russia in over two years after coming out as gay and speaking out against the war in Ukraine, said it took her some time to be at ease away from tennis.
"The first three weeks was a disaster," she said.
"It was really difficult. I just wasn't enjoying it. I found myself being super unhappy and in a really dark place.
"After six weeks I feel like I am finally recharged.
"I needed to do this to understand there are certain limits you can push through and then you have to give yourself space to stay a sane person."
The Brisbane International, one of the tune-up events for the Australian Open Grand Slam, begins on Sunday.