Two university professors from the Massachusetts Institute of Technology (MIT) looked into the amount of sleep students are getting and its relationship to the grades. The consistency of their sleeping habits as well as the time they go to bed also brings about a significant difference. Their study also shows that getting good sleep the night before the exams isn't good enough. It takes nights in a row to make a huge difference. 

Those are a few of the identified conclusions from an experiment that included 100 engineering students of the MIT. Every participant was given a FitBit, a wrist-worn device that keeps track of the user's activity 24/7. The researchers were able to collect a semester's worth of activity data from the device and used it for their study. Though surprising, but not really unexpected, the study was published in the Science of Learning journal by Kana Okano, an MIT Postdoc, John Gabrieli, Jeffrey Grossman, and two other authors. 

What was surprising was that for students who went to bed after a particular threshold tend to perform less in class, no matter how much sleep they end up getting. In the beginning, the study led by Grossmad was focused on finding the correlation between the academic performance of students and their physical exercise. In addition to wearing FitBit, he also enrolled 25 students to a special fitness class in MIT, hoping to see a measurable difference in academic performance between the two groups. 

The study showed that the students who weren't enrolled in the fitness class performed just as well as those who were enrolled in it. Grossman expressed his disappointment and speculated that the intervals between the classes and the fitness schedule was just too long to show even a bit of an effect. However, in the vast amount of data that was collected, several correlations became too obvious to overlook. 

While the devices were not programmed to track sleep, its algorithm was able to detect it primarily due to the lack of activity. The correlations on sleep and students' grades were not subtle. It showed how the students' grades were affected by the lack of sleep. Grossman recognized that there might be other contributing factors to students' grades than just sleep, but he expressed that "sleep really does matter."

Several studies in the past have shown how getting a good night's sleep leads to better scores, but the data collected shows that it is not about the sleep that students get the night before the big exam. Rather, it was the sleep the student is getting on days when they were learning that truly mattered. 

Another surprising finding was that there appears to be a cut-off time of good sleep, such that students who went to sleep at a later time had poorer performance, even if they got the same amount of sleep in total. "Quantity of sleep is not everything," Grossman says. The data showed that students who slept beyond 2 a.m. suffered from lower grades even if they got a total of 7 hours of sleep too. 

The quality of sleep students are getting significantly affected the study too. For example, the data showed that students who got consistently good sleep every night faired better than those who didn't. 

Further research may be needed to consider other factors that affect the relationship of sleep and the grades of college students. "I could imagine the exciting new studies that would be made in relation to what we did to understand the results more deeply," Grossman said.