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
fails to consider the possibility that frequent daytime napping is an effect rather than a cause of insomnia