Since sleep deprivation can affect awareness and our ability to focus, it can also affect our memory. In order to remember something properly, we have to focus on it and actively remember it by repeating it in our minds. This way, it is able to transfer from a fleeting memory (remembered for a few seconds), to a short term memory (memories held a few at a time) and afterwards, may be stored as a long term memory (stored memories, such as events, skills and knowledge). However, someone who is sleep deprived will be less alert and will have trouble transferring a fleeting memory to a short term memory and an even harder time making it a long term one. This is why it may be harder for someone to study if they are tired and they likely won't remember it as well later.
