A 7-year-old boy presents with his father to their pediatrician to discuss “severe nightmares” which have been occurring intermittently for six months. The father states that roughly once per week, his son starts screaming 2-3 hours after going to bed. The boy does not seem to respond to his father’s commands during these episodes, which ultimately self-resolve after a few minutes. The boy has no recollection of these events. Past medical history is unremarkable, and he does not take any medications. Vital signs are within normal range, and physical examination reveals age-appropriate physical and emotional development.
Which of the following features would most likely be present on electroencephalogram (EEG) at the time when this patient’s episodes occur?
B) Delta waves
Delta waves are large, high voltage waves and are a feature of the N3 stage of sleep. N3 sleep is the deepest stage of non-REM sleep and is the stage in which sleepwalking, night terrors, and bedwetting typically occur. It is important to distinguish night terrors (which are not remembered and occur during N3 sleep) from nightmares (which are remembered and occur during REM sleep)
Answer choice A: Beta waves, is incorrect. Beta waves are high frequency, low amplitude waves that are a feature of rapid eye movement (REM) sleep. REM sleep is the stage in which dreaming occurs. Beta waves are also present on EEG during periods of wakefulness.
Answer choice C: K complexes, is incorrect. K complexes are low frequency, high amplitude waves and are a feature of the N2 stage of sleep. N2 sleep is also characterized by sleep spindles.
Answer choice D: Sleep spindles, is incorrect. Sleep spindles are high frequency, crescendo-decrescendo waves and are a feature of the N2 stage of sleep. N2 sleep is also characterized by K complexes.
Answer choice E: Theta waves, is incorrect. Theta waves are a feature of N1 (light) sleep, which is also known as “relaxed wakefulness.”
Key Learning Point
The N3 stage of sleep is characterized by delta waves and is the stage of sleep in which sleep terrors, sleep walking, and bedwetting occur. A common mnemonic used to associate waves with sleep stages is “BATS Drink Blood”: Beta = awake; Alpha = eyes closed, not yet asleep; Theta = N1; Sleep Spindles = N2; Delta = N3; Beta = REM.
