To conduct this exercise within PubMed, please open a second browser window by clicking here.
In one search, find references about the relationships between circadian rhythms and either cortisol or melatonin in humans.
Find references about heart surgery. Notice how the term is mapped using the Search Details box on your results screen. Using History on the Advanced Search screen, combine this search with the previous search to find references about heart surgery, circadian rhythms and cortisol or melatonin in humans.
When you have finished this exercise, switch back to this window and compare your results with the suggested answer.