imagine that a researcher publishes the results from a study that indicate a statistically significant association between sleep deprivation and coronary disease. this result would mean that

This result would mean that . the findings are not likely to be due to chance fluctuations

Humans have different sleeping requirements (some need 8 hours, some only need 6, etc)  in order for our body to be properly functions, and these requirements are mostly influenced by genetics..
Because of this, the impact of sleep deprivation might influence the test subjects differently.