US researchers have discovered taking a nap while studying works even better if you dream about what you are trying to learn.
It has long been established that people who sleep after learning a task will perform it better when they wake up compared to people who do not nap.
Despite this, for many university students the all-night study session is an essential part of the lead-up to exam season.
"Cramming and getting it into your head is probably better than not studying at all. On the other hand, studying and getting a good night's sleep is probably better again," says Drew Dawson, director of the Centre for Sleep Research at the University of South Australia.
Dawson has been reviewing a study by researchers at the Harvard Medical School published this morning in the journal Current Biology.
"What was very interesting about this task was that people who reported dreaming about the task actually performed better than those who didn't dream about the task and even better than those who didn't sleep at all," he says.
To test their theory, the researchers taught people how to locate a specific shape somewhere in a computer-generated maze.
They made one group of participants have a nap before trying the exercise again. A second group of people were kept awake.
A third group were allowed to sleep, but the researchers woke them up several times to check whether they were dreaming.
"It is actually the first time people have actually been showing a very clear relationship between the dream content and changes at the neural level in the brain," Dawson.
Better for learning?
He says the research has broad implications, particularly for people who don't get enough sleep.
"It may be the case that there are some very important elements of learning that occur while we are sleeping and that those individuals that don't get sufficient sleep may actually have their learning compromised," he says.
Dawson says we may eventually get to a stage where it is possible to develop a program of learning that incorporates specific sleep breaks to maximise the amount of retention.
"When executives do it, it's called a power nap so I guess the answer is probably yes," he says.
"But there are also a lot of cultural sanctions against people sleeping on the job so to speak. It's not always interpreted in a positive sense.
"But whether you sleep during the day or sleep at night, I think the key message is if you short yourself on sleep and you don't get enough, it doesn't come without consequences."
Dr Colin Sullivan, a Professor of Medicine at the University of Sydney who specialises in sleep, says there is now a large body of evidence showing sleep has an important role not just in learning, but in creativity and mood as well.
"Seven and a half and eight hours sleep is fairly normal but we do also know that probably most people in the modern day get less probably by about an hour than what they need," he says.
Sullivan says sending everyone to bed an hour early may be the key to boosting the creativity and productivity of the nation.