Given a choice, Darrell would prefer to stay up until 1:00 a.m. and sleep until 10:00 a.m. This pattern is called the

Given a choice, Darrell would prefer to stay up until 1:00 a.m. and sleep until 10:00 a.m. This pattern is called the

• A. Secular trend
• B. Longitudinal design
• C. Delayed phase preference
• D. Tanner stages

Answer: (C)

Adolescents often experience a shift in their circadian rhythm that makes staying up late and waking late feel natural. The described pattern—preferring a 1:00 a.m. bedtime and a 10:00 a.m. wake time—fits a delayed phase preference, meaning the internal clock is phase-delayed relative to conventional daytime hours. This reflects normal timing changes in puberty, not a long-term generational trend, a research design, or physical maturation stages. A later melatonin onset and misalignment with early school schedules help explain why late sleep and late waking feel right for the individual.

Adolescents often experience a shift in their circadian rhythm that makes staying up late and waking late feel natural. The described pattern—preferring a 1:00 a.m. bedtime and a 10:00 a.m. wake time—fits a delayed phase preference, meaning the internal clock is phase-delayed relative to conventional daytime hours. This reflects normal timing changes in puberty, not a long-term generational trend, a research design, or physical maturation stages. A later melatonin onset and misalignment with early school schedules help explain why late sleep and late waking feel right for the individual.