Answer:
hypothesis
Step-by-step explanation:
A hypothesis is an idea or assumption which is usually based on rough observation or estimation. It could be termed an "intelligent guess", a supposition that is subject to scientific investigation to prove or disprove it based on scientific evidence. here the student has just made a statement that one would perform better if he gets more sleep, this is a general belief as we know one who doesn't get enough sleep might be unhealthy. However the student is yet to provide a scientific evidence to back this up.