Few study debates last as long as this one. Early risers swear by quiet mornings, night owls say their brain only switches on after dark, and productivity advice usually sides with the mornings. The research gives a more useful answer: the best time to study depends partly on your internal clock, but whatever time you choose, sleep decides how much of it you keep.
What chronotype means
Your chronotype is the timing of your internal body clock: when you naturally get sleepy, when you wake without an alarm, and when you feel most alert. Researchers usually place people on a spectrum from strong morning types (“larks”) to strong evening types (“owls”). Most people sit somewhere in the middle.
Two questionnaires are used most often. The Morningness–Eveningness Questionnaire, published by James Horne and Olov Östberg in 1976, asks about preferred times for sleeping, waking and doing demanding things, and was checked against people’s daily body temperature rhythms. The Munich ChronoType Questionnaire, developed by Till Roenneberg and colleagues, takes a different approach: it compares when you sleep on work or school days with when you sleep on free days, when no alarm is involved.
Chronotype is partly genetic, partly shaped by light exposure, and strongly linked to age. Using data from a very large sample, Roenneberg’s group found that people become later and later through adolescence and then shift abruptly back toward earlier sleep at around age 20. They proposed that turning point as a biological marker of the end of adolescence. In other words, if you are 17 and cannot fall asleep before midnight, that is your biology, not a character flaw.
Studying at your best time helps, a bit
Performance on many thinking tasks varies across the day, and it tends to be better when the time of day matches your chronotype. Researchers call this the synchrony effect.
One classic demonstration comes from a 1993 study by Cynthia May, Lynn Hasher and Ellen Stoltzfus. Most of the younger adults they tested were evening or neutral types, while most of the older adults were morning types. When memory was tested in the late afternoon, younger adults clearly outperformed older adults. In the morning, the difference disappeared. A 2007 study by David Goldstein and colleagues found a similar pattern in adolescents, who scored lower on intellectual tests when they were tested at their non-optimal time of day.
These effects are real, but they are not huge, and they vary by task. Your chronotype is a reason to schedule well, not a reason to give up on mornings or evenings altogether.
The twist: creative problems may prefer your “wrong” time
Not everything goes better at your peak. In 2011, Mareike Wieth and Rose Zacks gave people two kinds of problems at their optimal or non-optimal time of day. Analytic problems showed no consistent time-of-day effect. Insight problems, the kind that need you to drop an obvious approach and see the problem differently, were solved more often at the non-optimal time.
The likely reason is that when you are a little tired, you are worse at filtering out stray thoughts, and sometimes a stray thought is exactly what an insight problem needs. A practical way to use this: put the work that needs careful, step-by-step attention at your best time, and use your off-peak hours for brainstorming, outlining or looking at a stuck problem with fresh eyes.
How to find your own pattern
You do not need a lab. Try this during a holiday, or over a few free days without alarms:
- Note when you fall asleep and when you wake up naturally.
- Work out the midpoint of that sleep. If you sleep from 1:00 to 9:00, your midpoint is 5:00.
- Compare it with your school or work nights.
As a rough guide, a midpoint before about 3:00 points toward a morning type and one after about 5:30 toward an evening type, with most people somewhere in between. If you are catching up on lost sleep, your free-day midpoint will come out later than your true type, so a few days into a holiday gives a cleaner reading. The size of the gap between free days and school days matters too. Researchers call that gap social jetlag: the mismatch between your biological clock and the clock your timetable imposes. Late types tend to build up sleep debt during the week and then sleep in for hours on free days.
You can also track your alertness for a week: rate it from 1 to 5 every couple of hours and look for the peaks.
Sleep is what turns study into memory
Whatever time you study, the strongest research in this area is about what happens afterwards.
As early as 1924, John Jenkins and Karl Dallenbach found that people remembered material better after a period of sleep than after the same amount of time awake. A century of work since then, reviewed by Björn Rasch and Jan Born in 2013, has changed the explanation. Sleep does not just protect memories from interference. During deep, slow-wave sleep, the brain actively replays and reorganizes what it learned during the day, strengthening it for the long term.
Timing matters. In a 2006 study by Steffen Gais and colleagues, high-school students who learned vocabulary within a few hours before sleep remembered it better than those who stayed awake for many hours after learning, and the benefit did not depend on time of day.
Sleep before learning matters too. A 2007 study by Seung-Schik Yoo and colleagues found that a single night without sleep reduced activity in the hippocampus during learning and led to worse retention afterwards. A tired brain is worse at writing new memories in the first place.
So studying in the evening is not a problem in itself. Studying instead of sleeping is.
What all-nighters actually do
All-nighters feel productive. The evidence suggests that feeling is part of the problem. In a 1997 study by June Pilcher and Amy Walters, students who had been awake for 24 hours did significantly worse on a critical thinking test than students who had slept. The sleep-deprived students also rated their concentration, effort and performance higher. They could not tell how much worse they were doing.
A 2019 study at MIT, led by Kana Okano, gave activity trackers to students in a chemistry course and compared their sleep with their grades. Better quality, longer and more consistent sleep went with better results, and sleep measures accounted for nearly a quarter of the variation in performance. Interestingly, sleep on the single night before a test did not predict that test’s score. Sleep over the previous week and month did. One bad night before an exam is not a disaster. A term of short, irregular sleep is.
How much is enough? The US National Sleep Foundation recommends 8 to 10 hours for teenagers aged 14 to 17, and 7 to 9 hours for adults aged 18 to 25.
A plan for each type
If you are a morning type: do your hardest work, such as new material, problem sets or essay drafting, in the first half of the day. Use the evening for lighter review, flashcards and planning tomorrow. Protect your early bedtime, because that is what makes your mornings work.
If you are an evening type: schedule demanding work for late afternoon and evening, but keep a fixed latest bedtime so you still get enough sleep before morning classes. Caffeine is the usual trap: in a 2013 study by Christopher Drake and colleagues, a large dose (400 mg, the amount in roughly four cups of brewed coffee) disrupted sleep even when it was taken six hours before bed. Bright screens late at night can also push your clock later. In a 2015 study by Anne-Marie Chang and colleagues, people who read on a light-emitting e-reader before bed took longer to fall asleep and were less alert the next morning than people who read a printed book. If you need to shift earlier, morning daylight helps: Roenneberg’s group found that people who spend more time outdoors in daylight tend to sleep earlier.
If you are somewhere in the middle (most people): late morning and early afternoon are usually reliable for demanding work. A short walk or a change of task helps through the mid-afternoon dip.
For exams: if your exam starts at 9:00 and you are an owl, spend the last week or two gradually moving your schedule earlier and doing some practice papers at that hour. In the final days, prioritize sleep over extra hours of cramming. A light review the evening before, followed by a full night’s sleep, will usually serve you better than an all-nighter.
Putting it together
Find your natural pattern, put your hardest work where your alertness peaks, use off-peak time for creative or lighter tasks, and treat sleep as part of studying, not time taken away from it. Combine that with techniques that strengthen memory, such as spaced repetition, and plan your days with realistic breaks, as described in our guide to studying for long sessions.
If you study late, keep the sound low and steady. The homepage stream runs around the clock, and our article on background music and studying explains when music helps and when quiet is better.
Sources
- Horne, J. A., & Östberg, O. (1976). A self-assessment questionnaire to determine morningness–eveningness in human circadian rhythms. International Journal of Chronobiology, 4(2), 97–110.
- Roenneberg, T., Wirz-Justice, A., & Merrow, M. (2003). Life between clocks: Daily temporal patterns of human chronotypes. Journal of Biological Rhythms, 18(1), 80–90.
- Roenneberg, T., et al. (2004). A marker for the end of adolescence. Current Biology, 14(24), R1038–R1039.
- Wittmann, M., Dinich, J., Merrow, M., & Roenneberg, T. (2006). Social jetlag: Misalignment of biological and social time. Chronobiology International, 23(1–2), 497–509.
- May, C. P., Hasher, L., & Stoltzfus, E. R. (1993). Optimal time of day and the magnitude of age differences in memory. Psychological Science, 4(5), 326–330.
- Goldstein, D., Hahn, C. S., Hasher, L., Wiprzycka, U. J., & Zelazo, P. D. (2007). Time of day, intellectual performance, and behavioral problems in morning versus evening type adolescents. Personality and Individual Differences, 42(3), 431–440.
- Wieth, M. B., & Zacks, R. T. (2011). Time of day effects on problem solving: When the non-optimal is optimal. Thinking & Reasoning, 17(4), 387–401.
- Jenkins, J. G., & Dallenbach, K. M. (1924). Obliviscence during sleep and waking. The American Journal of Psychology, 35(4), 605–612.
- Rasch, B., & Born, J. (2013). About sleep’s role in memory. Physiological Reviews, 93(2), 681–766.
- Gais, S., Lucas, B., & Born, J. (2006). Sleep after learning aids memory recall. Learning & Memory, 13(3), 259–262.
- Yoo, S.-S., Hu, P. T., Gujar, N., Jolesz, F. A., & Walker, M. P. (2007). A deficit in the ability to form new human memories without sleep. Nature Neuroscience, 10(3), 385–392.
- Pilcher, J. J., & Walters, A. S. (1997). How sleep deprivation affects psychological variables related to college students’ cognitive performance. Journal of American College Health, 46(3), 121–126.
- Okano, K., Kaczmarzyk, J. R., Dave, N., Gabrieli, J. D. E., & Grossman, J. C. (2019). Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Science of Learning, 4, 16.
- Hirshkowitz, M., et al. (2015). National Sleep Foundation’s sleep time duration recommendations: Methodology and results summary. Sleep Health, 1(1), 40–43.
- Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11), 1195–1200.
- Chang, A.-M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 112(4), 1232–1237.
