What to know about post-traumatic stress disorder PTSD can affect people who experienced a traumatic event in any way.

For people suffering distress after experiencing a serious trauma, it can be hard to find any relief. Post-traumatic stress disorder has been reported to feel like being trapped in a room without any exits and can cause trouble with everyday activities like sleeping or functioning at work.

Even the singer Ariana Grande said she suffers from the troubling disorder known as PTSD after the Manchester Arena bombing during her concert on May 22, 2017 killed 22 people.

She said she doesn't think she'll ever be able to talk about the bombing without crying.

"It's hard to talk about because so many people have suffered such severe, tremendous loss," Grande said. "But, yeah, it's a real thing."

What is PTSD?

Post-traumatic stress disorder is a form of anxiety that can happen after experiencing or witnessing actual or near death, serious injury like car accidents or natural disasters, war-related violence, terrorism or sexual violence, according to the American Psychiatric Association.

While most people typically connect this disorder to military veterans or refugees, it can happen to anyone.

PTSD is not a sign of weakness and people can be affected by PTSD, even when they were not directly part of the traumatic event.

The exposure can happen to witnesses of a traumatic event in person, like for Ariana Grande, and to people who learn that the traumatic event happened to a loved one. Repeated or extreme exposure to details of a traumatic event, such as pictures or movies, can also cause PTSD.

What are the symptoms?

PTSD symptoms usually start after the traumatic event, but they may not appear until months or years later, according to the National Center for PTSD. They also may come and go over many years. Symptoms may last longer than one month, cause great distress, or interfere with a person’s work or home life.

Most people have four types of symptoms after the event and may not be the same for all: reliving the event, avoiding people or places, having more negative feelings and being in a state of hyper-arousal.

PTSD sufferers often relive the traumatic event over and over through bad memories, nightmares or flashbacks.

They may avoid people, places or things that are reminders of the traumatic event.

Over time, PTSD can also affect the way sufferers think about themselves and others. They often report having more negative beliefs and feelings. This can include feeling guilt or shame, losing interest in previously enjoyed activities, losing trust in others or even finding it hard to be happy.

Some PTSD sufferers enter a state of hypervigilance or hyperarousal, during which they are easily startled, overly alert and "on edge." They can sometimes be more aggressive or irritable and engage in reckless, self-destructive behavior. These states can also cause difficulty with concentration and sleeping.

How common is the disorder?

About 8 percent of people in the United States and Europe are affected by PTSD, according to the National Center for PTSD. There are some things that make it more likely to be affected by the disorder such as having a long-lasting trauma, getting hurt, or having a strong reaction the event.

PTSD is more than twice as common in women, according to the National Center for PTSD, possibly because women are more likely to experience sexual violence, and at least half of Americans have had a traumatic event in their lives.

How is PTSD treated?

PTSD treatment can be life-changing even if people have been struggling for years. Treatments are targeted at reducing the symptoms and "disturbances." There are two main types of treatment: psychotherapy, either counseling or "talk" therapy or medication.

Psychotherapy involves meeting with a therapist and sometimes a group. There are several approaches including trauma-focused therapy, prolonged exposure therapy and others, including group therapy. Eye Movement Desensitization and Reprocessing (EDMR) involves focusing on hand movements and sounds while recalling past trauma and can help the brain work through traumatic memories.

Medications such as antidepressants are a first-line treatment that can reduce the symptoms, but may take six to eight weeks to begin working.

Activities such as mindfulness, deep breathing exercises, stretching and yoga can sometimes ease symptoms.