ERBIL, Iraq — Aid agencies warned Monday that the 72-hour gap between Saturday’s Islamabad ceasefire announcement and its scheduled Wednesday start was producing a sharp and largely unanticipated spike in acute anxiety, sleep disorder and trauma cases across displacement sites from Iraqi Kurdistan to southern Lebanon, with the resumption of last-minute Iranian and Israeli strikes overnight shaking civilians who had, for the first time in six weeks, briefly allowed themselves to imagine an end.

Field teams from Doctors Without Borders, the International Rescue Committee and the Lebanese Red Cross said clinicians had logged a roughly 60 percent jump in walk-in psychological consultations at displacement-site clinics over the weekend compared with the preceding seven-day average, with the steepest increase among women between the ages of 20 and 45 and among adolescents separated from a parent during evacuation. The pattern, the agencies said, was consistent across camps with very different demographics — the simple fact of being asked to wait three more days.

“The ceasefire announcement did not bring relief. It opened a door, and people are standing in it,” said Dr. Hanaa Rashid, the IRC’s mental health coordinator for northern Iraq, who has been overseeing teams at four displacement sites around Erbil and Dohuk. “When the strikes were constant, the body was at war. When the announcement came, the body tried to come down. And then the strikes came again last night, and the body could not understand. That is when people break.”

Iran fired what Iraqi and Saudi air defense officials described as a final volley of medium-range ballistic missiles toward central Israel overnight Sunday into Monday, most of which were intercepted, and Israeli aircraft struck what the Israel Defense Forces described as a nuclear-related facility outside Arak in the early hours. Both sides have publicly committed to the cessation of hostilities at 00:00 GMT Wednesday but have signaled, in briefings to mediators, that operational tempo would not slacken until the clock ran out.

For the more than 1.9 million people the UN refugee agency now counts as displaced inside Iraq, Iran, Lebanon and Yemen, the announcement and the strikes have collided in ways the humanitarian system was not built to absorb. At the Baharka transit site outside Erbil, which has swelled to roughly 14,000 residents since late March, site managers said they had begun rotating volunteer “calm tents” through the night after families, hearing distant air defenses, ran from their shelters and began packing belongings to flee somewhere they could not name.

“They have been holding it together for forty-three days,” said Sirwa Mahmoud, a Kurdish psychologist who coordinates a roster of 22 volunteer counselors at Baharka. “They were told on Saturday that they could let go. Last night they heard the booms. Now their nervous systems do not know what they are supposed to do. The youngest children cry without a stimulus. The teenagers stop speaking. The grandmothers sit and wait, and that is its own kind of damage.”

The World Health Organization’s regional emergency office in Cairo issued a technical advisory Monday afternoon urging partner agencies to extend mental health triage hours through Wednesday morning and to delay any non-essential return movements until after the ceasefire took hold. The advisory, signed by WHO regional emergency director Dr. Rick Brennan, warned against what it called “premature normalization” — the tendency of families, once an end date is announced, to begin dismantling coping arrangements before the threat had actually ended.

“The day a ceasefire is announced is often the most psychologically dangerous day, because hope is the thing that, if pulled back too early, breaks people,” Brennan said in a telephone interview from Cairo. “We are asking partners to hold the line for 72 hours.”

In southern Lebanon, Lebanese Red Cross head of operations Georges Kettaneh said his teams had been instructed not to use the word “soon” with displaced families this week. “Soon is not a word people can hold anymore,” he said. “We say Wednesday. We say zero hours Greenwich. We give them the clock. The clock is the only thing that does not lie.”

The surge was being compounded by the exhaustion of responders themselves, aid officials said. Many of the local clinicians staffing displacement-site mental health programs were themselves displaced and grieving. A rapid assessment by the Inter-Agency Standing Committee’s mental health reference group, dated Sunday, found that 71 percent of local frontline staff surveyed across 38 sites met the threshold for what the group described as “operational burnout with elevated trauma load.”

“The people taking care of the people are the people,” said Layla Hassan, a Beirut-based regional analyst tracking the humanitarian response for a consortium of European donors. “There is no separate pool. The same Iraqi nurse who lost her cousin in Anbar is the one being asked to do crisis intervention with a teenager in Erbil at three in the morning.”

In Tehran, where international agencies have only intermittent access, the Iranian Red Crescent said in a statement carried by state media that it had opened four additional “psychological first aid” stations in metro stations across the capital and asked retired counselors and clergy to volunteer for the period through Friday. The statement did not mention the ceasefire by name but said the stations would remain open “until conditions in the city return to normal life.”

UN agencies said they were finalizing surge plans to be activated the moment the ceasefire took effect, including mobile mental health units to follow returning families along the main displacement corridors and a regional helpline expected to go live Thursday. Donors at last week’s Geneva pledging conference were being asked to consider an additional psychosocial top-up of roughly $180 million as part of a revised appeal expected later this week.

At Baharka, as dusk fell on Monday and the call to prayer rolled across the camp, Mahmoud said her team would keep two calm tents and a children’s tent open through the night for the third time in four days. “Two more nights,” she said. “We tell them two more nights. We will see what we have left on Wednesday.”