Sofia is walking home at dusk. As the amount of light reaching her eyes falls, three components help to control her sleep-wake cycle.
| Component | Description |
|---|---|
| X | This area of the hypothalamus receives information about light from the eyes and acts as the body's master clock. |
| Y | When X detects darkness, it signals this small gland in the brain. |
| Z | This hormone is released by Y, builds up in the blood during darkness and makes Sofia feel sleepy. |
Name component X.
Name component Y.
Name component Z, the hormone released by the structure identified in part (b).
53 exam-style questions on OCR GCSE Psychology 6.1 Key Concepts, covering 6.1.1 Functions, features and benefits of sleep, 6.1.2 Causes of sleep disorders, and 6.1.3 Endogenous pacemakers and exogenous zeitgebers. Each one has a worked solution and a mark scheme showing where the marks go.