Melatonin & Circadian Rhythm — NEET Biology
✅ Asked in NEET 2020Which of the following statements is correct about melatonin? (NEET 2020)
Which of the following statements is correct about melatonin? (NEET 2020)
Answer & NCERT explanation
Correct answer: B — Maintains circadian rhythm
Melatonin maintains circadian rhythm (biological clock). It's secreted by pineal gland, not adrenal medulla. Light suppresses melatonin secretion, darkness stimulates it, helping regulate sleep-wake cycles. It doesn't inhibit GH release or stimulate insulin secretion. NCERT mentions melatonin's role in biological rhythms and seasonal reproduction.
Read more NCERT concept on the PYQ
The pineal gland is located on the dorsal side of forebrain. Pineal secretes a hormone called melatonin. Melatonin plays a very important role in the regulation of a 24-hour (diurnal) rhythm of our body. For example, it helps in maintaining the normal rhythms of sleep-wake cycle, body temperature. In addition, melatonin also influences metabolism, pigmentation, the menstrual cycle as well as our defense capability.
NTA tests melatonin's role in regulating the 24-hour sleep-wake cycle and circadian rhythms. Students often confuse melatonin with other hormones like thyroxine or forget that it specifically controls diurnal (daily) rhythms. Key trap: thinking melatonin only causes sleepiness—it actually regulates multiple rhythms including body temperature, metabolism, and even menstrual cycles. Remember: pineal gland secretes melatonin in darkness, promoting sleep at night and maintaining all 24-hour body rhythms. This concept appears in competitive exams because it bridges anatomy, endocrinology, and physiology—making it a favorite NEET topic.
What does NCERT say about pineal gland located on?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.