Niko Cheng was ready to die in August. The 22-year-old nursing student and her fellow protesters known as “fighters” for their willingness to confront police in Hong Kong, had decided to make their last stand on 31 August.

Exhausted and weary after months of protesting, she had floated the idea of throwing herself at police and forcing them to fire on her. The other protesters talked her out of it. Still, she expected to be arrested or badly hurt.

But on the day of the march, Cheng was hit by a water cannon and forced to leave early. In the weeks afterward, instead of relief, she only felt a sense of malaise. When she lost her wallet, including her ID card, her first thought was that it didn’t matter.

“I had zero motivation to do anything. I just thought it was all useless, meaningless,” she said. “That’s when I realised I need to get my normal life back.”

As political unrest continues to roil Hong Kong, public health experts say a quieter and in some ways more dangerous battle is under way as more residents display signs of depression, anxiety, and acute stress.

Since June, protesters have tracked at least nine cases of suicides that appear to be directly linked to the demonstrations. Social workers fear more young people will take their lives as the protests enter their fifth month, with no sign of resolution and increasingly violent confrontations.

Q&A About this series Show Mental illness is universal, affecting hundreds of millions of people around the world. No country is spared, and when it comes to treatments, every country is a developing country. Causes are legion: stress, shock, grief, trauma (particularly if sustained in childhood). Naturally, conflict of any kind will generate many of these causative factors and increase the risk of mental illness in the population. Study after study has proven this to be true. This mini-series, part of the Guardian's global mental health project in 2019, hears from the people directly affected.

Photograph: Aaref Watad/AFP

Public health advocates, NGOs and counsellors say the number of calls and threats of suicide they have received has increased, especially in recent weeks.

It is not just the protesters who are at risk. A study by Hong Kong University released in July found nearly one in 10 were suffering from probable depression, as well as an increase in suicidal thoughts, from 1.1% at the start of this decade.

Gabriel Leung, head of the study, said that there was little difference in prevalence among those who did or did not attend protests, suggesting a “community-wide spillover effect.” Leung called the situation a “mental health epidemic”.

“The whole of society is suffering,” said Clarence Tsang, executive director of Samaritan Befrienders Hong Kong, an NGO focusing on suicide prevention. “This is generating a lot of pressure on the whole of society. At this big scale, it is affecting almost the whole population,” he said.

‘So tired of the life I was living’

For Cheng, that pressure has at times been too much. Between school, work and the movement, she often sleeps no more than four hours a night. After a fight with her father over the protests, she was kicked out and now stays with friends, moving every few nights. After months of seeing fellow protesters tear-gassed, arrested, and beaten by police, in July she first considered suicide.

“I was so tired of the life I was living and sometimes I would like to take a break but I would feel guilty. So I thought maybe it’s time for me. Maybe it is the last thing I can do for the protests, and I can take a break without any guilty thinking,” she said.

Public health experts say the protesters, many of them around Cheng’s age or younger, may not be equipped to deal with the exposure to violence and push themselves to extremes.

“Some of them are very young, very naive, very pure in their hearts. They just throw themselves in,” said Yip Siu Fai, director of the Centre of Suicide Research and Prevention at Hong Kong University. “They might not be psychologically mature enough. For them, the possible damage could be quite severe.”

We keep going on the street, but the government hasn’t responded so the youngsters will commit suicide to raise, to keep the noise of the movement up. Kevin Chiu, volunteer social workers.

Observers also worry the martyrdom of those who have killed themselves could encourage others. The nine “protest suicides” fuelled the early stage of the movement as victims were portrayed as making the ultimate sacrifice for the movement.

One of those is Lo Hiu Yan, a 21-year-old piano student, who fell to her death from an apartment building on 29 June. She had written on a wall: “Hong Kongers, we’ve protested for a long time, but we shouldn’t forget our faith. We must keep on.”

According to her friends, Lo supported the protests but she had not been consumed by them. Talkative, artistic, and empathetic, she was more focused on her hobbies, friends, and latest love interest, her friends said.

Her friends believe that for Lo, who had threatened suicide before the protests began, the unrest may have been a trigger but not the root cause. They also worry about the glorification of such deaths.

“Hero is not an appropriate word,” said Peter Leung, 21, a friend of Lo’s from university. “It is never worth it.”

Today, protesters cite the suicides as motivation. As the protests have shrunk, some have grown desperate, according to Kevin Chiu, 33, part of a team of volunteer social workers. Chiu has seen cases increase in the last few weeks.

“We keep going on the street, but the government hasn’t responded so the youngsters will commit suicide to raise, to keep the noise of the movement up,” he said.

Experts say the situation is not hopeless. Teams of volunteers on the messaging platform Telegram are on high alert and quickly crowdsource the location of suicide attempts. Social workers, sometimes paired with psychologists, rush to the scene.

“There is very strong interpersonal support among protesters and among those giving all kinds of support to them. I think that resilience and strength can act as a counterbalance,” said Yip Kim Ching, a clinical psychologist and part of a group of volunteer psychologists offering counselling.

Cheng is also adapting. She is focusing on her nursing degree and trying to mend ties with her family. To let out some of her anger, whenever she passes police she gives them the middle finger. She also runs every night in a park and is building up her strength.

She says: “I think things have some meaning now. At this moment, I’m still a nursing student. I’m still safe from the police. Maybe I can still save a lot of people.”

Additional reporting by Janice Hui

• International suicide helplines can be found atwww.befrienders.org. In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14.