Identifying Questions and Hypotheses

In this article, "Why Seven Hours of Sleep Might be Better Than Eight", I found that seven hours of sleep is probably better for the human body than getting eight hours of sleep. It said that several sleep studies concluded that getting seven hours if the optimal amount of sleep. The question of the study was "Is seven hours of sleep better than eight hours?". The author of the article makes a hypothesis "If getting too much sleep is unhealthy as well as getting too little sleep, then about seven hours of sleep is better for the body." The article says that experts generally recommend seven to nine hours of sleep a night. Getting less sleep at night, even if it's 20 minutes less, impairs bodily performance and function for the next day. Getting too much sleep can lead to health problems such as obesity, diabetes, and cardiovascular disease.
http://www.wsj.com/articles/sleep-experts-close-in-on-the-optimal-nights-sleep-1405984970