Another form of learning very similar to operant conditioning is classical conditioning. Both forms of conditioning have a stimulus that produces a response, however, unlike operant conditioning, classical conditioning forces an involuntary response to an unconditioned stimulus 281. Distributed study is much better than massed study. The reason is that mass studying only leads to fragmenting information and encoding it in an individual's short-term memory. Another concept is that when mass studying is combined with sleep deprivation, the student remembers less. General lack of sleep negatively impacts the student's ability to absorb material. For future individuals, it is best to avoid having sleepless nights due to lack of sleep and the fact that you are less likely to remember the material. All nights cause the material to remain in your short-term memory and there is no telling how long that memory will last. Individuals or students need to balance both their studies and their sleep schedule as both are essential for better quality learning sessions. This advice is more preferred, because it allows individuals not to avoid the subject and to have better success.