Should I cram all night before that exam?

By Karyn O'Keeffe 25/09/2012


I’m going to give a presentation to some law students in a couple of weeks. Along with providing information about normal sleep and what can affect it, I’d like to convey that short sleep is not a good strategy for optimising learning.

Short sleep amongst students is not uncommon. As a teenager, our circadian body clock naturally drifts later. Those late bedtimes and lengthy sleep-ins we see in teenagers are actually a normal physiological phenomenon. Our body clock generally returns to ‘normal’ in our early twenties. However, late bedtimes in teenagers and young adults, coupled with required early rise times due to school and other commitments, often means their sleep is cut short.

Alongside this, our behaviour can sometimes boost these changes in the timing of our circadian body clock. Most university students, at some time or other, have probably worked long hours after uni to pay the rent, worked all night on an assignment you really should have started two weeks ago because it’s due tomorrow, or simply gone out quite late and stayed out really late. Regular late night activity helps reinforce our body clock to later bedtimes and later rise times. More often than not, they lead to short sleep.

So how does short sleep relate to learning? Well, there are a number of studies in this area but a recent study in high school students showed that increased study time outside school was associated with decreased school performance (that is, understanding information in class or doing poorly on a test). However, after further analysis, it became evident that increased study time was associated with poor performance because it cut into sleep time.

This is not to say, of course, that increased study time is not beneficial for learning (there clearly is a relationship), but it does highlight that extending one’s daily activities at the expense of sleep, will likely lead to decreased academic performance the following day.