system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Sleep spindles and K complexes occur in which phase of the sleep cycle
assistant
The correct answer is  Sleep spindles are sudden bursts of oscillatory brain activity generated during stage 2 of NREM sleep.K complexes are large waves that react to external stimuli while sleeping also seen during stage 2 of NREM sleep.