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What is the minimum sleep you need before an exam?

  • Sean 

It’s important to get the minimum sleep you need before an exam for performance. According to the research, this is about 6 hours. This article explains why.

If you are struggling to prepare for your university exam you might be thinking of cutting back on sleep or even using a sleep aid like Melatonin the night before an exam. You should try to avoid doing this.

Instead, try to hit the minimum sleep the night before an exam and sleep well in the weeks leading up to it.

The night before your exam try and get a minimum of 6 hours of sleep. But beware that your sleep history the week or month before your exam is actually more important than this number. Just keep in mind that staying up to study instead of sleeping will only worsen your performance.

How Much Sleep do You Need at University?

There seems to be a decline in the amount of sleep a person needs as they age. However, for adults aged 18-60, the Centres for Disease Control and Prevention (CDC) recommends 7 or more hours of sleep each night.1 So this is what you should aim for as a university student.

Sleep has been demonstrated to be very important for academic performance. In a recent study, sleep accounted for 24.44% of the variance in overall grade performance.2 So you should care about your sleep habits in university. But why exactly does sleep matter? It seems that the answer has to do with memory.

Why sleep is important – How it affects memory

In order to know how sleep affects memory you need to know the different types of memory. The two broad categories of memory are declarative and non-declarative memory. Declarative memory consists of information that you are conscious of like factual information. Non-declarative memory is about things like muscle memory. Declarative memory is what will help you pass your exam.3

Much like memory, there are also different components to sleep. There are numerous studies linking sleep with memory consolidation. Consolidation is a process that strengthens memory by making it resistant to interference3. This works because sleep is broken down into stages. The last stage of sleep is REM (rapid eye movement) sleep and this stage seems to be the most important for consolidating memories.4

There is even evidence that this type of memory can be enhanced through sleep. This is a step above consolidation because it seems like sleep has the effect of extra practice when none took place.3

So now that we know how much sleep you need and why it matters for memory, how little can you get away with on your exam night?

What is the minimum sleep you need before an exam?

University student sleeping outside
How much sleep is enough?

A study was conducted that showed that how much you sleep the night before an exam matters up to a point for performance. Students with higher exam scores slept approximately 6-10 hours the night before their exams.2 However, there are many reasons you may need more than 6 hours of sleep the night before your exam.

Take 6 hours as a minimum number to aim for if you are crunched for time. However, take this number was a grain of salt. A massive caveat is that this study only looked at one night of sleep and not the student’s sleep history.

Your sleep history matters

Interestingly your sleep history about 1 month before the exam might be more important than just the single night before the exam. Research has found that sleep duration and quality over the 1 week to 1 month beforehand mattered more for exam performance than just the night before.5 So if your exam is still 1 week away make to sleep well for the whole week!

If you have a good sleep schedule then your sleep the night before an exam is relatively less important (but still important). But if you are reading this article it’s unlikely that you fall into this camp. So how much should you sleep if you have a poor sleep history?

How to recover from bad sleep before your exam

Research indicates that if you are sleep-deprived you need more than a single night to fully recover. This is because your brain adapts to poor sleep and operates consistently at a reduced performance level to compensate and this can delay recovery. Severe sleep deprivation (3 hours per night for 7 days) can be improved quite quickly, although not fully, with even just a single 8 hours of the night of sleep. However, if you are only moderately to mildly sleep-deprived this will not help.6

It has actually been found that even 1 full week of good sleep is not sufficient for a full recovery to baseline performance levels.7 Once again, if your exam is a week away try and get some good sleep leading up to it, ideally more than 1 week of recovery is needed. Although you can still make a significant improvement in just a single night if your sleep has been quite bad recently.

You may be tempted to think that, if my sleep history matters more than just the night of the exam, and full sleep recovery can take a long time if my sleep isn’t that bad, then I should just stay up and study right? No.

Should you study or sleep the night before an exam?

If your exam is tomorrow or much closer you should still try and get a good night’s sleep. While sleeping the week before would have been best, the research still indicates that exam performance is higher when you sleep more the night before an exam compared to less2 and if you are severely sleep-deprived that you can have a rapid performance improvement from sleeping more.6 Sleeping the night before is still better than staying up and studying.

When we think back to the enhancing effects of sleep-dependent memory consolidation4, this becomes even more clear. If you choose to sleep you solidify what you already have and might even enhance it a bit further.

It seems like you can have your cake and eat it too here. You can sleep and learn at the same time because your memory will be enhanced.

Different people need different sleep

Finally, it is important to note that people are all different and that what has been demonstrated by research might not work for you individually.

Genetic differences in sleep

Some people simply need different amounts of sleep.8 I have met people who say that they have always slept for 12 hours each night and if they sleep less they do not feel good. While this isn’t common it points out that everyone is different in their sleep preferences and what feels good.

Some people consider themselves midnight owls and others consider themselves to be morning people. Some people simply feel more awake and alert at night compared to the day and this difference is actually genetic in a lot of cases. This has to do with differences in our internal biological clocks.8

A the end of the day you need to do what results in you feeling the best when you sleep. Take the research p as a general rule of thumb to start with. But try and fine-tune how much sleep you really need before an exam based on your personal preferences.

The Takeaway

In university, you need about 7 or more hours of sleep per night. Sleep is important and this is especially true when it comes to the consolidation of declarative memories during REM sleep. When it comes to being ready for your exam a minimum to stick to is about 6 hours. But keep in mind that your sleep history the week or month before your exam is actually more important. However, this doesn’t mean you should stay up and study. The benefits of sleeping rather than studying the night before an exam are still clear, even if this is the second-best option.


  1. Consensus Conference Panel. (2015). Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 38(6), 843–844.
  2. Fakhari, A., Kheradmand, N., & Dolatkhah, N. (2016). Sleep Duration the Night before an Exam and Its Relationship to Students’ Exam Scores. British Journal of Medicine and Medical Research, 15, 1–6.
  3. Walker, M. P., & Stickgold, R. (2004). Sleep-Dependent Learning and Memory Consolidation. Neuron, 44(1), 121–133.
  4. Stickgold, R. Sleep-dependent memory consolidation. Nature 437, 1272–1278 (2005).
  5. Okano, K., Kaczmarzyk, J.R., Dave, N. et al. Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Sci. Learn. 4, 16 (2019).
  6. Belenky, G., Wesensten, N. J., Thorne, D. R., Thomas, M. L., Sing, H. C., Redmond, D. P., Russo, M. B., & Balkin, T. J. (2003). Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: a sleep dose‐response study. Journal of Sleep Research, 12(1), 1–12.
  7. Ochab, J. K., Szwed, J., Oles, K., Beres, A., Chialvo, D. R., Domagalik, A., Fafrowicz, M., Oginska, H., Gudowska-Nowak, E., Marek, T., & Nowak, M. A. (2021). Observing changes in human functioning during induced sleep deficiency and recovery periods. PloS One, 16(9), e0255771–e0255771.