Catherine Zeta-Jones has checked into a clinic with depression after supporting her husband, Michael Douglas, in his fight against cancer.
Despite the illness, the actor's publicist, Cece Yorke, insisted she was "feeling great" and was planning to start work on two films this week. He said: "After dealing with the stress of the past year, Catherine made the decision to check into a mental health facility for a brief stay to treat her bipolar II disorder."
The illness is a form of manic depression but differs from bipolar disorder in that the manic episodes are less extreme.
Douglas underwent radiotherapy and chemotherapy after being diagnosed with throat cancer last summer. In January it was announced that he had beaten it.
Mark Davies, from the charity Rethink Mental Illness, said the condition is "distressing and potentially severe". He praised the Oscar winner for admitting to it publicly: "There is still a lot of stigma around mental health which often means that people stay silent and try to fight the illness on their own.
"When people such as Catherine Zeta-Jones speak out it makes a big difference to the millions of other people facing mental illness. It shows them that they are not alone and that mental illness can affect anyone."
Zeta-Jones was awarded a CBE in February. She rose to fame in the television series The Darling Buds of May.