Good news if you're a lover of an afternoon nap - it's been found that having a snooze can give you the same boost as a cup of coffee.
Sleep expert Dr. Nicole Lovato, from Adelaide Institute for Sleep Health, has found that dozing off could actually even be better than reaching for a hot drink, as it means sleep won't be disrupted later that night, a known side effect of caffeine.
She further found that short bursts of power napping, between 10 and 15 minutes, can significantly improve alertness, cognitive performance and mood almost immediately after waking, with the effects lasting for a few hours.
"Our research (not yet published) has found those who regularly nap report feeling more alert after a brief nap in the afternoon when compared to those who only nap occasionally," said Dr. Lovato, writing for The Conversation.
"Another research group found that motor learning, which is where brain pathways change in response to learning a new skill, was significantly greater following a brief afternoon nap for regular nappers when compared to non-nappers.
"In fact, the overall benefits of naps are similar to those experienced after consuming caffeine (or other stimulant medications) but without the side effects of caffeine dependence and possibly disrupted sleep at night time."
Through her research, Dr. Lovato discovered that 50 per cent of people take a nap at least once per week.
She also looked into sleeping for longer periods of time, explaining that long naps can be enjoyed, but it's advisable to time them so you don't wake up too groggy.
"If you are planning to stay up later than usual, or if taking a little longer to fall asleep at bedtime is not bothersome, time your nap for about 1.5 hours," she outlined. "This is the length of a normal sleep cycle. You will experience deep sleep for about an hour or so followed by light sleep for the last half an hour.
"Waking up during light sleep will leave you feeling refreshed and alert. However, waking during deep sleep will not."
Meanwhile, in separate research by a team from Washington University in St. Louis, it was found that dozing off or napping at inappropriate times could be an early warning sign of Alzheimer's disease.
"In this new study we found people with pre-clinical Alzheimer's disease had more fragmentation in their (sleep-wake) activity patterns - with more periods of inactivity or sleep during the day and more periods of activity at night," said senior author Dr. Yo-El Ju.
Study results have been published in JAMA Neurology.