Which hormone is higher in the late afternoon/PM due to diurnal variation?

• A. Cortisol
• B. Growth hormone
• C. Aldosterone
• D. Prolactin

Answer: (B)

The main concept here is diurnal variation in hormone secretion. Growth hormone shows a clear circadian pattern: although its largest release happens at night during slow‑wave sleep, there is also a smaller daytime peak in the late afternoon. That means levels tend to be higher in the late afternoon/early evening compared to earlier in the day, even though the big surge occurs during sleep.

Cortisol, in contrast, rises toward the morning and declines throughout the day, so it’s not higher in the late afternoon. Prolactin tends to rise during sleep and at night rather than in the late afternoon. Aldosterone varies less with the time of day and doesn’t have a pronounced late‑afternoon peak.