Context: For temperature studies, subjects must remain awake but calm and semi-reclined in near darkness while their rectal temperatures are taken continuously. Though variation is great among normal chronotypes, the average human adult's temperature reaches its minimum at about 05:00 (5 a.m.), about two hours before habitual wake time. Baehr et al. found that, in young adults, the daily body temperature minimum occurred at about 04:00 (4 a.m.) for morning types but at about 06:00 (6 a.m.) for evening types. This minimum occurred at approximately the middle of the eight hour sleep period for morning types, but closer to waking in evening types.

Question: What physical factor must be continuously monitored during temperature studies> 
Answer: temperatures

Question: At what time does the average adult human reach his lowest temperature?
Answer: 05:00

Question: How long before wake time is the lowest temperature reached?
Answer: two hours

Question: When does the temperature of morning type young adults reach its lowest?
Answer: 04:00

Question: What is the time of lowest temperature for evening type young adults?
Answer: 06:00

Question: What physical factor must be periodicly monitored in temperature studies?
Answer: Unanswerable

Question: What do evening types reach at 4:00 a.m?
Answer: Unanswerable

Question: What occurs close to waking for morning types?
Answer: Unanswerable

Question: Who reaches their minimum temperature in the middle of their waking hours?
Answer: Unanswerable