A "Bad Dream," also known as a nightmare, is a distressing or frightening dream that can cause feelings of fear, anxiety, or sadness upon waking. These dreams often involve scenarios that are unsettling, such as being chased, falling, or experiencing loss. Nightmares can occur during the REM (Rapid Eye Movement) stage of sleep, which is when most dreaming happens. Bad dreams can affect people of all ages, but they are particularly common in children. Factors such as stress, trauma, or certain medications can increase the likelihood of experiencing nightmares. While they are usually harmless, frequent bad dreams may disrupt sleep and impact overall well-being.