All-nighters are no-brainers. Especially if it is the night before the exam, sleep deprivation will hurt you cognitively. Concentration, reaction time and decision skills are weakened resulting in poor test performance.
Avoid excessive caffeine. Some side-effects are restlessness, rambling flow of thought and speech, gastrointestinal disturbance, nervousness, and muscle twitching. The rebound let-down and fatigue actually make you feel more tired.
There is a best time to sleep. You need a minimum of three hours and the best times to sleep are between 2AM and 6AM. Your body heat is lowest from 3-4AM, so you are drowsiest then and your memory retention is extremely poor. Sleep helps the mind absorb and retain the information you reviewed while studying.
Tips on staying alert while studying: