C3.1.11—Melatonin and sleep
Melatonin and sleep links named stimuli, coordinating structures and effectors so body systems or plant tissues produce an integrated biological response.
- Syllabus
- First assessment 2025
- Objective
- C3.1.11
- Level
- HL
Exam analysis
Chance of appearing5%of analysed past papers
Latest appearanceNovember 2025
Most common paperPaper2
Typical marks1
Common command terms
- Explain
- Identify
- Describe
- State
- Deduce
- Outline
Scoring notes
- Common mistake
- Describing melatonin as a general energy hormone instead of a sleep-timing signal.
Recent exam appearances
November 2025Paper1A ["HL"] · TZ327[ 1 ]C3.1.11—Melatonin and sleep
May 2025Paper1A ["HL"] · TZ228[ 1 ]C3.1.11—Melatonin and sleep
May 2023Paper2 ["HL"] · TZ12(d)[ 2 ]C3.1.11—Melatonin and sleep
November 2022Paper1 ["HL"] · TZ025[ 1 ]C3.1.11—Melatonin and sleep
May 2022Paper2 ["HL"] · TZ24(c)[ 1 ]C3.1.11—Melatonin and sleep
Practice this objective
Coverage 2016–2025 · Updated 16 Jul 2026
Concept essentials
- Melatonin and sleep depends on linking the stimulus to the coordinating structure or signal.
- The pathway for melatonin and sleep must keep information flow and response direction clear.
- Named tissues, hormones, neurons or effectors give melatonin and sleep its biological specificity.
- Evidence about melatonin and sleep is strongest when structure, mechanism and outcome are connected.