As anyone who has ever pulled an all-nighter knows, the crash that follows consecutive hours of studying can be inevitable.
Scientists have found that sleep deprivation can have a negative impact on memory capacity as well as affecting long-term physical health and well-being.
Jessica Dunphy, a UCLA alumna, remembers being rushed to the emergency room after vomiting in class during a final. She had crammed the night before for a solid 18 hours.
“I wouldn’t eat, sleep, shower, wouldn’t brush my teeth. … I was just so focused on getting a good grade,” Dunphy said.
She added that she had felt she needed the pressure of cramming in order to do well on her tests.
“I couldn’t focus if I wasn’t under pressure. … I would pull all-nighters all the time ““ sometimes two in a row,” Dunphy said.
Dunphy, who now weighs 97 pounds, said that she still suffers daily vomiting, diarrhea, nausea and short- term memory loss, all side effects she believes are related to her previous study habits.
“In the middle of writing a research paper or studying for a test, I would lean over to the side … throw up in a trash can, and then go back to studying,” Dunphy said.
Dr. Gina Poe, a professor of anesthesiology at the University of Michigan, said that while it isn’t known if people can fully recover from the effects of sleep deprivation, missing sleep can be harmful in the long run.
“When animals (lab rats) don’t sleep, they die,” Poe said.
In fact, testing has shown that lab rats can survive from three to five weeks before they perish from a breakdown of the immune system. For people, the symptoms of sleep deprivation are visible right away.
“When people don’t sleep, they start to crave junk food, their metabolism increases, and their bodies get colder. … The immune system breaks down after a certain time. It’s stressed to the max because it’s sleep deprived,” Poe said.
According to Poe, REM sleep, or rapid eye movement sleep, is essential for memory recall.
“Sleep loss affects reconsolidation. When you’re reviewing material, you take it off of your memory shelf, dust it off, and then reshelve it. But when you have had no sleep, you don’t put the information back in the right spot ““ it’s disorganized,” Poe said.
Poe mentioned that a lack of sleep can mean that material a student has attempted to learn at the last moment simply won’t stick ““ the brain won’t “get” it. Poe’s research maintains that REM sleep solidifies what has previously been learned, acting as a kind of “housekeeping” by strengthening unconsolidated memories and erasing memories that would counteract what has just been learned.
But Poe also mentioned that a complete lack of sleep could be devastating for a student attempting to use critical thinking or problem solving skills, which require more REM sleep.
In fact, Poe asserted that such students would be better off with two hours of sleep than none ““ a guarantee of at least some REM sleep.
“In rat studies, if you deprive a rat of REM sleep after the first four hours that they’ve learned something new … even if you allow them to make up for the deprivation in the next 12 hours, they won’t remember it,” Poe said.
She added that the ability to problem-solve and process information is in part based on REM cycles.
“If you are conductively learning something, the night’s sleep that you get just before is kind of the aha moment. That kind of sleep includes a lot more REM sleep than normal and more dense rapid eye movements … especially since REM sleep is important for both solidifying the things that you’ve just learned and for reorganizing the brain so that it’s refreshed and ready to learn,” Poe said.
However, Poe maintained that rote memorization is not dependent on sleep, making it easier for students taking multiple-choice tests requiring simple memorization to cram to their heart’s content.
But this approach, while possibly ensuring a good grade, also ensures that the memorized material won’t be available later.
Dr. Gary Small of the neurology department at UCLA says that cramming often involves “state-dependent learning,” or recall that is enhanced by placing the body in the same conditions as the initial exposure.
“If you’re sleep deprived when you’re studying, you’ll do better on the test if you’re sleep deprived as well,” Small said.
But then, Small said, you crash, and the material is permanently erased from your memory stores.
“It’s not a great technique for long-term building,” Small said, adding that cramming could spell disaster for a student attempting to learn cumulative material.
Dunphy, who now works as a recruiter, admits that she doesn’t remember anything from those long, arduous nights of studying.
But Dunphy, who is currently undergoing a series of blood tests to find a cure for her inability to keep down food, also finds that her short- term memory is impaired.
“It’s harder than before to remember little things,” Dunphy said.
Though research is still being done on the long-term effects of sleep deprivation, scientists are sure of one thing. Sleep isn’t just essential for health ““ it’s a vital tool for memory as well.