( CNN ) -- Most of us wake up from nightmares relieved that we 're safe in bed . But a small fraction uncontrollably act out their dreams as they unfold , endangering themselves or others . The recent movie `` Sleepwalk With Me , '' about a struggling stand-up comedian and his issues with sleep , brings to light a rare condition called REM behavior disorder . This film is not a documentary , but lead actor and director Mike Birbiglia has said that many events , including the dangerous behaviors while asleep , are based on his real life . Matt Pandamiglio , Birbiglia 's character , drives hundreds of miles to any comedy gig he can possibly get to , away from the girlfriend he is n't sure he wants to marry . In the midst of all this , Pandamiglio experiences dramatic episodes of acting out his dreams . For instance , while staying at a hotel alone , he jumps through the window of his room because , in his dream , he 's being pursued by a missile targeting him . Although the film is called `` Sleepwalk With Me , '' Pandamiglio is n't sleepwalking per se -- he 's kicking , running , climbing on top of things and falling off them . After repeatedly delaying a doctor 's visit , he finally gets the diagnosis of REM behavior disorder , which affects less than 1 % of the population , according to the American Sleep Association . Unusual patterns of behavior that people exhibit while sleeping are called parasomnias . Most of them are most likely to happen when a person is sleep-deprived and under stress , said Philip Gehrman , assistant professor of psychiatry at the University of Pennsylvania . Sleepwalking and REM behavior disorder are two examples of parasomnias . Sleepwalking happens during non-REM sleep ; it usually involves walking around and perhaps mumbling . Comedian Birbiglia on truth and fiction in 'Sleepwalk With Me ' REM is a stage of deep sleep during which certain parts of the body are normally paralyzed temporarily . `` The brain sends out the signals to move , but at the level of the spinal cord , the motor neurons are inhibited , '' said Dr. William C. Dement , a pioneer in the field of sleep research and professor at Stanford University School of Medicine . But that inhibition fails in REM behavior disorder , allowing the person to move in the way that he or she is envisioning in a dream . `` It can be very dangerous , '' Dement said . REM behavior disorder and sleepwalking are defined as separate disorders , but in reality there may be some overlap , Dement said . Dement and Dr. Rafael Pelayo , associate professor at Stanford medical school , said they have never seen patients who jumped out of windows , but some have punched windows . Dement appears as himself in `` Sleepwalk With Me , '' sitting in the passenger seat beside the struggling comedian while he 's dreaming/listening to Dement 's audio book in the car . ( It 's a little reminiscent of Cornel West 's cameo in `` The Matrix Reloaded , '' another widely known academic in surreal circumstances . ) `` In the simplistic way of thinking , the brain is either awake , sleeping or dreaming , '' Pelayo said . `` But we know that the brain is complicated enough that one part can be awake while another part can be sleeping at the same time . '' In sleepwalking , the rational part of the brain is offline , while the emotional part is activated , he said . Most people with REM behavior disorder are men , and they tend to be older , Pelayo said . The disorder can mark the start of Parkinson 's disease . It 's unusual for someone as young as Birbiglia , 34 , to exhibit REM behavior disorder , Pelayo said . But it 's possible that he has a combination of sleepwalking and REM behavior disorder , he said . The film portrayed Birbiglia 's character exhibiting several risk factors : drinking alcohol , staying up late , sleeping in different environments and being under stress . Sleepwalking by itself is more common , especially among children . Research suggests that as many as 30 % of children have experienced sleepwalking . Most people stop once they hit puberty , Gehrman said . Sleepwalking has occurred among nearly one in three Americans at some point in their lives , a study in Neurology found in May . As for whether someone should awaken people who are in one of these altered sleep states , it 's more dangerous for others than for the sleepers , experts say . The sleepers ' brains will not be impaired by waking up , but they may react violently . Sleepwalking among adults is not necessarily a problem . For mild cases , education about the phenomenon and reassurance are enough , Gehrman said . But if the person goes outside and gets into dangerous situations , he or she may need to sleep more and undergo stress management interventions . If that does n't work , especially among people who have been sleepwalking for their whole lives , medications may be necessary . The drug that sleepwalkers tend to start with is the anti-anxiety medication clonazepam , Gehrman said . It 's not clear why it works , but it may help people relax and sleep more deeply . Clonazepam is also prescribed for REM behavior disorder , although it is sometimes not appropriate in older patients because it may aggravate sleep apnea , Pelayo said . There 's evidence that the hormone melatonin can be effective . Some people do n't respond to any medications for sleepwalking , Gehrman said . It may help to put a bell on the door so that if they try to leave the bedroom , they will wake up -- or at least their bed partner will , he said . In extreme cases , people need restraints so that they ca n't get out of bed during the night , Gehrman said -- something that attaches them to the bed in such a way that only someone who is awake could undo it . Birbiglia has said in interviews that , as with his alter ego in the film , he takes medication and sleeps in a sleeping bag , and he used to wear mittens so that he could n't open the bag . Gehrman has n't had any patients who have tried the bag-and-mittens method but noted , `` You have to be creative sometimes . '' Experts say there is n't a lot of research going on into sleepwalking or REM behavior disorder treatments since the available resources are sufficient in most people . The next step in REM behavior disorder is exploring the connection to Parkinson 's disease , Pelayo said . It may be possible to identify patients for whom the sleep disorder is a risk factor for Parkinson 's and treat them before the disease gets worse . Have you ever had an episode of sleepwalking or other sleep disorder ? Tell us about it in the comments .
It has occurred among nearly one in three Americans , group says . REM behavior disorder affects less than 1 % of the population , group says . Stress and lack of sleep can cause sleep disorders . Medications are available for more serious cases .