Naps can be divisive.
Some people swear by them, noting the improved prowess of their mind after a short kip, while others hate them, complaining that they feel even more tired, groggy and disoriented after a rest. Some say they don't work at all.
What if our love or hate of naps had less to do with the individual, and more to do with the length time our siestas last for?
This week, Insight is looking at whether we are getting enough sleep in our increasingly busy lives.
Neurologist Dr Fiona Kerr, from the University of Adelaide, helped dispel some myths about our napping habits, pointing out that the right type of sleep can make us more efficient, skilled in complex problem solving, and creative.
She identified four different stages of the humble nap:
Stage 1 nap: The catnap
Length: 10 mins maximum
Usefulness rating: 4
Kerr remembers numerous occasions where she's been so tired just resting her head on her desk, or in her hands, has sent her into a catnap.
It's got her through some important meetings, but ultimately a nap that doesn't last longer than 10 minutes isn't particularly helpful.
Some things do improve: "You'll feel a bit more alert ... but it's subjective and it only lasts a couple of hours," says Kerr. "It's a bit like coffee."
Like the caffeinated beverage, the immediate feeling of being more alert masks the continuation of tiredness symptoms, including high levels of mistakes and poor memory.
In an emergency it may work, but it's unlikely to make any lasting impact on your brain function and thinking power.
Stage 2 nap: The power nap
Length: 15-20 mins maximum
Usefulness rating: 8
This is the ideal type of midday rest. Before your body starts to settle in for a full cycle of sleep, there's just enough time to file away a few things and refresh the mind for further work.
"[It] allows the inbox, if you like, of your real working memory - the mind that we're using all the time just sitting here thinking about things, listening - to empty," says Kerr.
"So we sort of get rid of stuff and then it allows us to be more alert and more effective and for our memory to improve a little bit."
Other benefits include improved motor function, mood and creativity. Stress levels can go down, and in the long term it can decrease the risk of heart attack and weight gain.
Kerr says there are a number of companies already identifying the power of the stage 2 nap.
"At Google, if you don't have your twenty minute nap you're asked why, because they know just how much it increases capacity and alertness."
A prototype sleeping "pod". Source: Getty Images
Stage 3 nap: The Valley of Death
Length: 30-60 mins maximum
Usefulness rating: 0
As the name would suggest, an especially dangerous form of napping.
It's the type of kip that will leave you feeling vague, murky-headed, perhaps a little more tired than when you put your head down.
Kerr explains:
Your body [and] your brain thinks you're going to go into a full REM cycle. So the frontal lobe powers down, if you like, and that's when you get that really horrible kind of fuzzy grogginess.
There appears to be minimal benefit to this type of nap.
In medium-length naps the frontal lobe of the brain begins to power down, leaving a feeling of grogginess. Source: Getty Images
Stage 4 nap: The full cycle
Length: 60-90 mins maximum
Usefulness rating: 9
Arguably the best type of nap you can take, a longer rest is essential if you're looking to be more creative, to solve complex problems, or to learn something quite complicated.
That amount of time gives you a full cycle of REM sleep, which allows our brains to file away information, form new ideas and improve memory.
"If you've got a really tough problem, it sounds really counterintuitive sometimes when you haven't got time ... [but if] you have an hour's nap, all sorts of things then connect across and you get a huge level of all sorts of chemicals [that] make you feel a lot more positive," says Kerr.
On a bigger level, this kind of sleep later at night is important for the same reasons: to help file away information gathered from the day and transfer it into long-term memory.
"If you don't sleep enough, you don't embed what you've learnt, you actually lose that information," says Kerr, pointing to one of the bigger problems Insight is exploring tonight around sleep and its impact on our health.
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