A woman stands on a rooftop listening to the sounds of the city below. There is only the dull hum of traffic tonight. But she knows how easily that can change. It is usually the dogs who notice the sound first and begin to bark furiously. The noise of aircraft. Then the ominous percussion of explosions. A ball of orange rising from an airstrike in a familiar neighbourhood.

The BBC has obtained footage and interviews from Tehran which evoke a city of strained nerves, of constant waiting for the next blast and relentless fear of the state security apparatus.

Baran – not her real name – is a businesswoman in her thirties. She is now too scared to go to work. "With the start of the drone attacks, no one dares to go outside. If I open my door and step out, it is like gambling with my life."

She lives alone but is in constant communication with her friends. "My friends and I message each other constantly asking where everyone is…and even when there is no sound the silence itself is terrifying. I am doing everything I can to stay alive and witness whatever lies ahead."

Like so many young Iranians, Baran saw her hopes of change devastated in recent months. Thousands of people were killed in a crackdown by regime forces in January after widespread demonstrations demanding change.

"I cannot even remember how I used to live in the past without being reminded of the loved one I lost during the protests," she says. "I fear tomorrow. I fear the person I will be tomorrow. Today, I survive somehow, but how will I get through tomorrow? That is the real question. Will I even live through tomorrow?"

Now repression is total. Open dissent is impossible as the state's watchers are everywhere. Footage we obtained shows regime supporters driving through the city at night, flags flying from their cars – a message to any who might be tempted to protest.

The official narrative is the only one allowed. State television broadcasts footage of demonstrations and funerals. Interviews with pro-regime officials and protestors offer repeated denunciations of America and Israel. In government propaganda the Iranian people are extolled as willing to suffer martyrdom.

Independent journalists still try to gather testimony that offers a credible alternative view, but they run the risk of arrest, torture and possibly worse. As one of them told me: "In wartime conditions you really don't know what they are capable of doing."

It is only in their homes that some of Tehran's residents feel able to share their feelings. Like Ali, a man in his forties, middle class and educated, who had hoped the killing of Ayatollah Khamenei at the start of the war would bring change.

Now he sees the streets around his home filled with security forces. Armed and masked men have set up checkpoints. "It is painful when I go into the streets. The city looks like the city of the dead." He is taking anti-depressants, to "keep myself normal" he says.

"I see groups of people in the streets who are not from among us at all; they are people who support the government and who have, in effect, taken the streets away from us."

Several Iranians who have spoken to the BBC describe conflicting emotions. They want the regime out but feel they and their country are under attack.

"The situation is frightening…," says Ali. "The skies of your country are controlled by enemy forces. But at the same time there is always a hope in people's hearts. It's not that we are supporting America or Israel. But hoping simply that for one moment, something might happen that ends the current Iranian regime, and that the people will be able to create change."

In her flat Baran is listening for the sound of explosions and messaging friends in other neighbourhoods. "Do you know what the difference is between our sky and the sky of the rest of the world?" she asks. "They sleep under the stars at night, and we sleep under rockets. Both skies give light, but different kinds of light."

Baran thinks the war may go on for years, and that its psychological effects will last even longer. "This war will not end soon, because this war is inside our homes, inside the families…The war has entered our blood and has entered our lives."

The citizens of this 6,000-year-old city are living in dread of American and Israeli bombs. Of the regime and its torturers. A daily unrelenting dread from which there is no sign of escape.