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Across 5. We may find it difficult to think clearly if we wake in the middle of the night, because cortisol is not ......... enough for alertness 7. Aschoff and Wever placed participants in one of these 8. Type of light that was not controlled adequately in early research into the sleep-wake cycle 10. Czeisler et al found that people's sleep-wake cycles vary from this to sixty five hours 11. Theories and studies of circadian rhythms are arguably this in their approach 12. There is a slight ........ is core body temperature after lunchtime each day 13. A study of a blind man with a natural circadian rhythm of 24.9 hours shows how important our ...... is, and that exogenous zeitgebers cannot always reset our endogenous pacemakers 14. The Siffre experiment is this kind of study 16. Core body ........... is an example of a circadian rhythm 17. Bollani concluded that the core body temperature rhythm must be this, because babies are unlikely to be responding to exogenous zeitgebers 19. Follow a circadian rhythm 21. Kelly et al's sample was made up of these 24. Evidence that hormones follow this kind of rhythm comes from drugs that only work at certain times of the day, because they need the hormone to be at its peak for the medication to be effective 25. This hormone is circadian, peaking at around midnight 27. A blind man with a circadian rhythm of 24.9 hours had to take these at bed time in order to follow a circadian rhythm like everyone else 29. Folkard et al found that this kind of recall is best when we are in the peak heat of the circadian rhythm of core body temperature 31. Kelly et al's sample followed an 18-hour day; 6 hours working and 12 hours off-duty, but they maintained a ........ hour circadian rhythm 32. Area where Siffre spent time with no external cues in 1962 35. Our core body temperature is this at about 6pm each day 36. This researcher manipulated participants' circadian rhythms using only artificial light 37. Our core body temperature is this at about 4.30am each day

Down 1. Famous for doing experiments in caves 2. Aschoff and Wever found that most people's circadian rhythms were twenty four - twenty five hours, but some were as long as ......... 3. The study of how timing (chronos) affects drug treatments (therapy) 4. This type of person prefers to rise and go to bed early (circadian cycle onset = 6am) 6. These differences in sleep-wake cycles mean we cannot generalise from one person to the next 9. Hord and Thompson did not find one of these when looking at core body temperature and cognitive performance in field studies 12. After this many days, Bollani's baby participants showed a 24-hour core body temperature rhythm 15. Kelly et al found that it is ....... to override endogenous circadian rhythms using exogenous zeitgebers 18. A .........-running sleep-wake cycle is usually just over 24 hours 20. This hormone is lowest at around midgnight 21. A blind man with a circadian rhythm of 24.9 hours had to take these in the morning in order to follow a circadian rhythm like everyone else 22. Folkard et al's findings have implications for what time of day people should take these 23. The sleep-.......... cycle is an example of a circadian rhythm 26. Folkard et al linked the circadian variation on core body temperature to these abilities 28. This type of person prefers to wake and go to bed later (circadian cycle onset = 10am) 30. Siffre's use of the experimental method - controlling key variables - mean he was able to demonstrate a .......... relationship 33. Cortisol peaks at around ........ am each day 34. Cortisol is produced when we're stressed but is also associated with making us feel this in the morning