You're asleep, right? You can hardly be expected to control your actions, much less your thoughts. But if bad dreams are ruining your sleep (and affecting your waking moments), you can work to eliminate or minimize them, according to psychologists and sleep experts.

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How nightmares work 

"One way of thinking about dreams is that they're part of the same problem-solving processes that we use during the day time," Gregory White, a California-based clinical psychologist and psychology professor at National University, told U.S. News and World Report. "If you're really distressed, you're more likely to have distressing dreams."

In turn, a night of bad dreams can leave you feeling depressed or angry the next day, and repetitive sleep loss can cause a slew of negative side effects, from poor performance to obesity. Long-term sleep loss can even lead to mental illness.

Professor of psychiatry, Tore Nielsen, who directs the University of Montreal's Dream and Nightmare Laboratory, told U.S. News about his research, which showed excessive numbers of nightmares are frequently linked to mental health problems including anxiety disorders, PTSD, depression and even a higher risk of suicide.

"Fortunately, there are effective treatments for nightmares," he added, like rehearsing the "bad dream script" with a more positive ending, or treating nightmares and anxiety disorders simultaneously.

A woman suffers from insomnia.
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Know the ordinary causes

According to Psychology Today, nightmares occur during rapid eye movement (REM) sleep and result in feelings of extreme fear, horror, distress or anxiety. "This phenomenon tends to occur in the latter part of the night and often awakens the sleeper, who is likely to recall the content of the dream," according to PT, which detailed these common causes:

  • Anxiety or stress. "In 60 percent of cases, a major life event precedes the onset of nightmares." The death of a loved one is a common trigger.
  • Illness with a fever
  • An adverse reaction to a prescription drug
  • Recent withdrawal from a drug, especially from sleeping pills
  • Excessive alcohol consumption or abrupt alcohol withdrawal
  • A breathing disorder during sleep, e.g. sleep apnea

How to fight nightmares

Writing in Physchology Today, Susan Krauss Whitbourne looks at recent nightmare research and recommends the following steps for those suffering from nightmares:

  • Put your worries to rest before bedtime. It's a good idea to clear your head of your day's annoyances and unpleasant events. Instead, focus on the positive events that happened to you during the day.
  • Avoid ruminating on negative experiences. If you tend to dwell on the negative, try to stop this habit, Whitbourne advised. "Catch yourself when you're envisioning worst-case scenarios or when you're starting to get down on yourself for feeling the way you do. Reducing your negative emotions while you're awake can make it easier for you to engage in Step 1 of putting them on hold when you're ready to go to sleep."
  • When you do have nightmares, don't catastrophize them. "Catastrophizing" is the psychological term for imagining the worst possible outcome of a negative experience. As a result, the "magnitude of the experience skyrockets beyond its original negative impact," Whitbourne explained. "The nightmares that stick with you the following day may contain horrendous images. Dreams do not predict the future. If you worry that the bad things you dreamt about will happen, you will only increase your negative mood state."
  • Learn to distinguish an actual dream from a waking nightmare. Sometimes you may actually be half awake when you think you're asleep. Recognizing this may help you see that you're allowing your negative emotions to cascade.
  • Watch what you eat. Probably the best known cause of bad dreams (and the fuel for many a cartoon and sitcom plot) is the link between indigestion and nightmares. This really is a thing, according to  Woman's Day, which recommended avoiding foods that could cause indigestion near bedtime. For rest that's more peaceful all around, eat dinner at least two hours before bedtime, and choose nighttime snacks wisely, including no milk products for the lactose intolerant and no caffeine after 2 p.m. Read more here.