Linkin Park lead singer Chester Bennington hanged himself at his LA home on July 20, as did Soundgarten vocalist Chris Cornell in May and actor-comedian Robin Williams three years ago.

All of them had struggled with depression for years.

Closer home, Deepika Padukone, Ranveer Singh, Karan Johar and Ileana D’Cruz put the spotlight on depression, and Anushka Sharma took the stigma out of getting treated for anxiety and panic attacks.

Depression tends to creep up on you when you least expect it, which often makes it difficult to diagnose. It becomes all the more difficult when you have all the trappings of success: fame, money, good looks and a supportive family.

Because then no one considers depression as a possible destroyer of your mood. After all, how can someone who has everything be unhappy? So they label you “difficult” and put your emotional withdrawal or outbursts, as the case may be, to moodiness and temper.

Everyone feels down and out sometimes, but most snap out of it within days. Some don’t, and struggle every day with feelings of listlessness, ennui, guilt, low-self-worth, sleeplessness, appetite loss (or gain), and difficulty concentrating.

Deepika said for her the downer started as a feeling of “a strange emptiness in my stomach”. Like most people, she put it down to work stress and she did what most of us would do: ignore it.

“I thought it was stress, so I tried to distract myself by focusing on work, and surrounding myself with people, which helped for a while… but the nagging feeling didn’t go away,” she wrote in her exclusive piece for Hindustan Times.

“Depression is not always about moping and weeping all day. Highly-functional people can be normal in the company of others, yet be plagued with feelings of emptiness and inadequacy when alone,” says Dr Samir Parikh, head of psychiatry and behavioral sciences, Fortis Hospitals.

“They can keep up appearances and function socially, yet feel low and depressed when alone,” he says.

Depression affects 121 million people worldwide, estimates the World Health Organisation (WHO). It can affect a person’s ability to work, form relationships and often causes physical symptoms such as sleeplessness and listlessness.

Worldwide, more than 8.5 lakh (850,000) people die from suicide each year, which roughly corresponds to one death every 40 seconds. It’s among the top 10 causes of deaths across the world. In India, self-harm is the seventh most common cause of deaths in India, reported The Global Burden of Diseases Study, 2013.

“Ninety percent of people who commit suicide have a psychiatric disorder and 75% are clinically depressed,” says Dr Parikh. Depression is an equal opportunity illness that affects people in different forms across ages and social strata. “If feelings of sadness, social withdrawal and listlessness do not go way in two weeks, the person must see a doctor,” says Rajesh Sagar, associate professor, department of psychiatry, All India Institute of Medical Sciences (AIIMS).

Increasing, more people in India are seeking treatment for depression. Antidepressants sales in value has shot up by more than 30% over the past four years, up from Rs 760 crore in 2013 to Rs 1,093 crore in 2016.

Drugs and treatment are a must if the condition is chronic (lasts for more than four weeks), recurrent (bouts of depression occur three four times a year) or the mood interferes with your ability to function normally for more than two weeks.