Without external cue, the sleep-wake cycle in humans: (A) Unchanged, (B) Continues with cycle length of > 24 hours, (C) Continues with cycle length of < 24 hours, (D) Continue with cycle length of > 12 hours
Answer is B. Normal sleep-wake cycle in humans- 24 hrs
When external cues (Light and darkness) removed, sleep-wake cycle- Slightly increased (>24hrs)