Use of case studies and small samples

• studies of the Sleep/wake cycle tend to involve small groups of participants as in the experiment by Aschoff and Wever or studies of single individuals as in the case of Siffre
• The people involved may not be representative of the wider population and this limits the extent to which meaningful generalisations can be made
• in his most recent cave experience in 1999, Siffre observed, at the age of 60, that his internal clock ticked much more slowly than when he was a young man
• this illustrates the fact that even when the same person is involved there are factors that vary which may prevent general conclusions being drawn