Most students believe that staying up late to study is a smart way to prepare for an exam. Psychologists, , have that sleep plays an role in . While we , the brain information from the and moves into long-term . Students sleep well after studying usually remember more than those who stay awake all night.

Researchers recommend that young adults sleep for seven to nine hours each night. Yet university students far less, during their first . New , late-night events and heavy lists all for their . The is often a cycle of tiredness and poor concentration.

For a long time, sleep was seen as a period when the brain simply switched off. Research over the past few decades has shown the opposite. During sleep, the brain is highly active, and some of this activity appears to strengthen memories formed during the day.

New information is first held by the hippocampus, a small structure deep inside the brain. During deep sleep, the hippocampus appears to “replay” recent experiences, and these memories are gradually stored in the outer layer of the brain, the cortex, where they become more stable. Scientists call this process consolidation.

In one common type of experiment, participants learn a list of word pairs and are tested several hours later. Those who sleep between learning and testing usually remember more than those who stay awake for the same number of hours. Sleep before learning matters too: people who have been deprived of sleep find it harder to take in new information the next day.

For students, the message is clear. A night without sleep before an exam may give extra hours for reading, but it can weaken the very memories the student is trying to build.

Many parents complain that teenagers stay up late and are impossible to wake in the morning. It is easy to call this laziness, but biology offers a better explanation.

Our sleep is timed by an internal clock, called the circadian rhythm, which runs on a cycle of roughly 24 hours. One signal of this clock is melatonin, a hormone that rises in the evening and makes us feel sleepy. During adolescence, melatonin is released later at night than in childhood. As a result, many teenagers do not feel tired until close to midnight, even if they go to bed earlier.

This shift usually continues into the early twenties, which means that many first-year university students are still biologically late sleepers. When early classes force them to wake at 7 a.m., they lose sleep night after night.

Some schools have responded by starting the day later. Studies of these schools have reported that students sleep longer and attend class more regularly. Not every school can change its timetable, however, so researchers also encourage students to keep regular sleep times and to limit bright screens late at night.