An adult follows three different evening routines. Each routine is followed for several days before the mean sleep-onset time is recorded.
| Routine | Evening light | Evening meal | Mean sleep-onset time |
|---|---|---|---|
| A | Bright light until 23:00 | 18:00 | 00:20 |
| B | Dim light from 21:00 | 18:00 | 22:40 |
| C | Dim light from 21:00 | 21:00 | 23:10 |
In Routine D, the adult will experience bright light until 23:00 and eat the evening meal at 21:00.
Using ideas about endogenous pacemakers and exogenous zeitgebers, explain the pattern in the results and whether the mean sleep-onset time in Routine D is likely to be earlier or later than 00:20.
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.