When a parent falls seriously ill, the home is often shaken.
Family relationships are tested and children, depending on their age, may be frightened and confused at the unfamiliar sight of their parent's weakness.
The adults may be exhausted and at a loss, and wrestle with how to help their children cope.
Children need to know that someone they trust is in charge, according to experts.
Ms Chan Lay Lin, senior principal at the Medical Social Work department at the Institute of Mental Health, says: "Leadership by the remaining parent or other adult family members can provide a stable and safe environment for the children.
"Wherever possible, changes in the routines of the children should be kept to a minimum and their daily practical and emotional needs continue to be provided. Sometimes, this may require help from extended family or close friends."
Illness brings family closer
It started as a stiffness in his left arm which Mr Jason Foo, then a car sales executive who was keen on tennis and golf, attributed to tennis elbow.
Within a year, the stiffness spread to the entire left side of his body.
"In 2009, I was diagnosed with Parkinson's and I accepted that I was experiencing its early onset at the age of 45," says the father of two, now 50, referring to the progressive neurological disorder. His sons Edwin and Edward were then 15 and 12.
A year later, Mr Foo was retrenched. His sales had dropped dramatically, says his wife, housewife and caregiver Lena Lim, 49.
"I couldn't concentrate or talk for too long, and my job required me to have active conversations with customers," he says, adding that his speech is slurred and he is unable to smile, due to weakened facial muscles, during his "off" periods.
Medication helps him function "almost normally" but when its effects wear off, ordinary tasks such as holding a cup and taking money out from a walletcan become challenging, says Mr Foo, who adds that he took extra medication to do this interview with SundayLife!.
He says he has felt frustrated, helpless, lonely and depressed. With illness and weakness, there can be a "monster in the house", as he describes it.
"I lost that feeling of leadership. I can be 'off' at the wrong time, where I have difficulty speaking, for example, when I want to speak to my two boys about important things at school," he says. "I feel I'm burdening my wife. I feel guilt. I used to be the head of the household... As a father, you will tend to not want people to help you, but deep down, I want to be helped."
Sometimes what is meant for good may be taken as bad, says Ms Lim. "I have to stay positive to support him, so much so my husband sometimes felt I don't accept his disability," she says.
Older son Edwin, now 20 and about to enlist for national service, would offer assistance to Mr Foo the instant he saw he needed help. Younger son Edward, a 17-year-old student at Lasalle College of the Arts, would wait for his father to ask for help, wanting Mr Foo to do the maximum he could to help himself first.
Neither approach was wrong, says Ms Lim, who adds that the illness has meant she has "to be the middle person, moderating between father and sons".
Mr Foo says: "I don't feel hurt anymore if the children don't volunteer. If I ask them, they will help ungrudgingly."
Edward, who is pursuing a diploma in performance, says: "The different ways my brother and I reacted were how we would want to be treated.
"I want my father to have the joy of doing as much as he can himself - it just takes more time. I like that he might have struggled, but he made it. That's how he brought me up: Try your best, don't be afraid to fail. It was an honour to have the chance to show what I learnt from him.
"He used to take care of me. Now, I feel great joy to be able to help my father. I've grown up much faster because of this."
For a year, Mr Foo and Ms Lim kept his diagnosis from their children, fearing the news would affect Edwin's N-level examinations and Edward's Primary School Leaving Examination. The boys heard the news after their examinations.
Recently, Mr Foo told his sons he is entering the second phase of Parkinson's, where the disability is more pronounced. He adds: "It was easier to say than the first time. Communication is important. You need to inform your family members about the issues you face. Don't leave your children out of your illness."
Even with the "monster in the house", "the family has got closer", says Mr Foo, who now works part-time in customer service.
"My wife and I grew closer because we talk at a much deeper level now. I appreciate her, more than before the illness."