In the nineteenth century, authors believed that nightmares were caused by not having enough oxygen, therefore it was believed that those with sleep apnea had more frequent nightmares than those without.Straight outta nightmares 3d shirt The results actually showed that healthy people have more nightmares than the sleep apnea patients. Another study supports the hypothesis. In this study, 48 patients (aged 20–85 yrs) with obstructive airways disease (OAD), including 21 with and 27 without asthma, were compared with 149 sex- and age-matched controls without respiratory disease.
OAD Ss with asthma reported approximately 3 times as many nightmares as controls or OAD Ss without asthma. The evolutionary purpose of nightmares then could be a mechanism to awaken a person who is in danger.