rendering the study to be a waste of time
this is not a nice approach of questioning a work. The data are not "trustable", "legitimate" or "valid" would be better choices of words.
The author's view about the relation between the amount of sleep needed by the executives and the success of their firms becomes biased by a recent study on certain executives which showed greater profit margins and faster growth by those executives who need less than 6 hours of sleep and without even examining the fallacies of the study the author asserts that only such people should be hired.
this is a very long sentence, and the absence of commas made it really difficult to read.
reported
you could use the words "records", "the available documents", "evidence", "proofs", and the like, instead of repeating one word.
executives
you could also use the word "subjects", cause those male and female executives are subjects in this study.
Second, the study does not state the amount of work given to these executives.Whether or not it was the same as those needing more sleep ? The work may have been relatively minuscule compared to those needing more sleep , and that may have lead to the successful completion of the work, inturn making it succesful.
can u see the repetition?
Certain executives doesdo not represent all the
hope this helps.
Cheers,
Ahmad