The nurse is caring for a young-adult patient on the medical-surgical unit. When doing midnight checks, the nurse observes the patient awake, putting a puzzle together. Which information will the nurse consider to best explain this finding?

A) The patient misses family and is lonely.
B) The patient was waiting to talk with the nurse.
C) The patient has been kept up with the noise on the unit.
D) The patient's sleep-wake cycle preference is late evening.

This patient is awake and alert enough to do a puzzle. The individual's sleep-wake preference is probably late evening. All persons have biological clocks that synchronize their sleep-wake cycle. This explains why some individuals fall asleep in the early evening, whereas others go to bed at midnight or early morning. Waiting to talk with the nurse, being lonely, and noise on the unit may contribute to lack of sleep, but the best explanation for the patient being awake is the biological clock.