Cramming means studying intensively over a short period of time, just before an examination. It is, in general, a practice followed by students who want to cram most of the information in their heads in a short amount of time. Cramming might help you to score well in the exam, it reduces the long-term retention of the topic.
If you want to move information from your short term memory to your long term memory, periodically reviewing the information is the most important thing.
Let’s talk about Spacing Effect to learn more about long-term retention in detail.

Source: CASA at http://casa.tamucc.edu

The spacing effect is the phenomenon whereby learning is greater when studying is spread out over time, as opposed to studying the same amount of content in a single session. It is interesting to note that spaced presentation of information does not benefit short retention intervals, where massed presentation (cramming) is better performer, but it leads to a longer retention period.
The graph is a plot of percentage of retained information versus the time. We can see that with cramming, we have a high short term retention but we forget that information with time. Whereas, spaced presentation of information helps to retain the information longer even spending lesser and lesser time for every exposure to the information.
Along with this loss of long term retention of the information, students also lose their sleep or adversely affect their sleep cycle due to those all-nighters done to cram the information before the examination. According to University of California, Los Angeles (UCLA), sleep is also an important factor in scoring well in the exams along with studying. Research has shown that in ninth grade, the average adolescent sleeps 7.6 hours per night, then declines to 7.3 hours in 10th grade, 7.0 hours in 11th grade and 6.9 hours in 12th grade. So this shows that students lose sleep while coming into their high schools and during the competitive exams

This graph shows how sleep increases the retention of the information as compared to recalling the same information after remaining awake. This shows how cramming without taking a sleep before the exam can affect your information retention.
We have seen how cramming affects the long term retention and sleep of the students which both affect the performance of the students in the long run.

How can you apply this?

For reviewing the information periodically, Let’s do a small activity:

Make some flashcards with name of the topics written on it. Make 5 boxes named 1 to 5. Put the topics you know the least in box 1 and the most in box 5. Make a habit of studying Box 1 cards once a day, Box 2 cards every 3 days, Box 3 cards every 5 days and so on. Look at cards in every box everyday and if you get a correct answer, the card gets promoted to the next box. Any incorrect answer card is sent to Box 1. Repeat this till you get all the cards in the Box 5.

You can do this activity for topics of every chapter. Suppose you are learning mole concept, make different cards for all topics like molarity, molality stoichiometry and so on. Review these cards periodically and repeat the activity for these cards. After completing this activity for every chapter, all the concepts will be embedded in your long term memory.

The next thing that needs to be done is to Stop avoiding your sleep. You need to sleep atleast 8 hours before your exam to get the best out the information you learnt. Never review all the information one night before the exam but learn it periodically.