why do we have nightmares

Nightmares occur primarily during the rapid eye movement (REM) stage of sleep and are thought to be linked to the brain's way of processing emotions, stress, and trauma. They may serve as a mechanism for the mind to work through unresolved fears or anxieties experienced during the day. Factors that commonly trigger nightmares include stress, anxiety, trauma (such as accidents or abuse), sleep deprivation, certain medications, substance misuse, mental health disorders like PTSD, and even scary books or movies before bed. Nightmares can be more frequent in people with mental health conditions and those with disrupted sleep patterns, such as from sleep apnea or irregular sleeping schedules. Essentially, nightmares may reflect the brain's attempt to deal with emotional distress and threats, sometimes acting as a signal that something in waking life needs attention.