How Dreams Work

Many people have the same or a similar dream many times, over either a short period of time or during their lifetime. Recurring dreams often emerge during times of stress. They have many different themes, but there are some subjects that pop up frequently, like being chased or failing a test. These dreams can be positive or negative.

Sometimes, recurring dreams are symptoms of PTSD or generalized anxiety disorder. They may represent a way to process trauma or practice avoiding threats, but it's not completely clear why they occur.

Nightmares are dreams that are so distressing they usually wake us up, at least partially. Nightmares can occur at any age but occur in children more than adults. Nightmares usually cause strong feelings of fear, sadness or anxiety. Their causes are varied.

Some medications (or withdrawal from them) cause nightmares. Traumatic events also cause nightmares. Recurrent nightmares are also associated with acute stress disorder, anxiety and depression. Persistent nightmares can have a range of adverse effects — they can cause sleep deprivation, they can interfere with relationships and they have been linked to self-injury and suicide.

If a health condition is contributing to the nightmares, then treatment addresses that underlying condition. Some sleep centers offer nightmare therapy and counseling. Nightmares associated with PTSD have been treated with imagery rehearsal therapy, where the affected person changes the ending to the nightmare while awake so the dream is no longer threatening.

People with PTSD, depression or anxiety also may take medication to alleviate the feelings leading to their nightmares. People who have nightmares could also benefit from lifestyle changes like exercising, practicing relaxation techniques and avoiding stimulants before bed.

Another method of treating nightmares is through lucid dreaming. Lucid dreaming may allow people to reduce the frequency, intensity and distress of nightmares, but more research is needed to form clearer conclusions.

Unlike nightmares that occur during REM sleep, night terrors generally occur during non-REM sleep, usually in the first cycle of the deepest phase of sleep (within the first hour or two of going to bed). Night terrors can last anywhere from a few minutes to 30 or 40 minutes.

People having night terrors are still asleep but may look like they are awake. For example, they may sit up in bed screaming with their eyes wide-open. When they actually do wake up, they usually have no memory of the episode (although some people do remember them). Night terrors occur most frequently in children, but adults can also experience them.