There's nothing like an afternoon nap for a quick pick-me-up.
When your eyelids are drooping and your energy levels are dropping, a quick snooze can make the world of difference.
After all, there are countries where the entire working day has been built around having a doze in the afternoon.
And don't forget we lost an hour of sleep at the weekend when the clocks went forward.
But sometimes you can wake up from a nap and feel, frankly, much worse than you did before you went to sleep.
Was it too long? Was it too short? Was it the wrong type of sleep?
We decided to ask insomnia specialist Kathryn Pinkham what we should know about napping. Here's what she said.
Are regular naps good for your health?
"In general, regular napping is not a good idea," said Kathryn, founder of The Insomnia Clinic, which works in areas including Nottingham, and has a therapist working out of Mapperley.
"We need an appetite for [night-time] sleep, and having a nap is like having a snack - it reduces the appetite.
"Napping regularly in the day continues a cycle of not sleeping at the right time."
What about occasional naps?
That's not to say that the occasional nap isn't a good thing. "Used in the right way, it's an okay measure to boost your energy," said Kathryn.
"It's a short-term measure, to recharge your batteries for three or four hours and take the edge off your tiredness.
"But ultimately you need to sort out your night-time sleep."
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What's the ideal length of time for a nap?
This is the crucial point.
Kathryn said that the perfect nap should be 20 to 25 minutes long.
Any shorter than this and you're not getting any benefit.
Any longer, and there are a couple of problems you could encounter.
If you sleep for around 45 minutes you'll be too deep into a cycle, and that can leave you waking up feeling groggy and worse than you did beforehand.
If you push through to around 90 minutes you'll overcome this problem, and probably wake up feeling refreshed. But it is likely to affect you later on when you struggle to get off to sleep at night..
"You will go through a proper sleep cycle, but it will definitely interfere with your night-time sleep," said Kathryn.
What's the best time of day for a nap?
You should take your nap in the afternoon, but before 4pm. Any later and you're getting too near to your bedtime sleep.
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