Psychologist: A study of 436 university students found that those who took short naps throughout the day suffered from insomnia more frequently than those who did not. Moreover, people who work on commercial fishing vessels often have irregular sleep patterns that include frequent napping, and they also suffer from insomnia. So it is very likely that napping tends to cause insomnia. The reasoning in the psychologist's argument is most vulnerable to criticism on the grounds that the argument ['fails to consider the possibility that frequent daytime napping is an effect rather than a cause of insomnia', 'presumes, without providing justification, that university students suffer from insomnia more frequently than do members of the general population', 'presumes, without providing justification, that there is such a thing as a regular sleep pattern for someone working on a commercial fishing vessel', 'presumes that all instances of insomnia have the same cause']