Feeling tired? Not enough sleep last night?

I know waking up at the crack of dawn isn’t everyone’s cup of tea, but why wouldn’t anyone want to be out and about in an incredible place like Londolozi at this time of day? Could it be that we stayed up too late last night? You are not used to getting up so early? Or are the beds are far too comfortable to leave? (Almost!) Most of the time it is just simply we feel like we haven’t got enough sleep.

Each individual being different, humans roughly need between six and eight hours sleep a day. Most of the time we get it all in one go, at night. Without this sleep, we simply cannot function at full capacity, and in turn resort to numerous cups of coffee to help us through the day.

Out in the wild the animals survive just fine without their daily dose of caffeine. Lions are renowned for their uncanny ability to be found sleeping the majority of the time, getting in about 20 hours of shut-eye each day. However, unlike the sleep we enjoy, lions sleep in what we would call cat-naps. A very light sleep in which one could be easily woken and are always mildly alert, ready to react at a moment’s notice. But being the apex predator they can afford to take the extra nap.

Sleeping Mapago brothers

Lions; the most renowned sleepers of all.

On the other end of the spectrum, and one that I find absolutely fascinating is the giraffe, only requiring around 30 minutes of sleep a day! It is difficult to even fathom getting through a week with only about four hours of sleep, IN TOTAL!! With such little, I would start to lose my mind, quite literally. Sleep deprivation has been used as a torture method through the ages, yet when humans would be going insane, giraffes would be feeling like they’d overslept!

Giraffe, the champions of the power-nap.

Sleep is a time for our body to regenerate and recover. So with a lack of sleep come numerous side-effects such as impaired thinking and memory and depression of some vital signs. Various studies into sleep deprivation in humans showed an increase in blood pressure, pulse, body temperature and impaired cognitive abilities. Long and short-term memory decreased, creative thinking and problem solving also took a tumble. Many people also reported hallucinations, and further research found that although still awake, the brainwaves of these people still match those associated with the normal 90 minute REM (Rapid Eye Movement) sleep cycle. This is when we dream, meaning that the hallucinations were in fact dream imagery making its way through while the people were still awake. All pretty scary don’t you think?

So why do giraffe need such little sleep?

Being the tallest animals on the planet they have access to the best available leaves that other animals can’t reach. Like most herbivores giraffe are ruminants, spending up to 50% of their day feeding, an extra 30% having to re-chew partially digested food – the cud – which is regurgitated up from the rumen. A further 10-15% of the day is spent walking between feeding spots or pursuing females/avoiding males, leaving a significantly small period left to sleep. Ruminating can be done while walking, standing or lying down, but during this time the giraffe cannot drift off into a deep sleep. Otherwise it runs a high risk of choking on the cud, and so needs to keep its head held up.

Laying down is an awkward move for giraffe, and a dangerous one, as their reaction time to stand up again is just long enough to let a lion rush in and pounce on them.

Laying down in giraffe is a tremendous task in which they fold their legs under their bodies, and fold their neck around and rest it on their rump to drift off into a deeper sleep. Of course this exposes them to much greater risk of predation, as their primary means of defence is to run and to kick. It takes a good couple of seconds for the giraffe to wake up, stand up and run away if a predator approaches, which would be more than enough time for a lion to rush in and pin the giraffe by the neck. In order to reduce the risk of being pounced on by a predator they only ever sleep in very short increments of no longer than 5 minutes.

Being capable of sleeping while standing is part of their evolutionary adaptation, but is also in done in short bursts. Giraffe are able to enter a period where they are ‘half-asleep’, with eyes half open and ears constantly twitching.

I don’t think I will ever be able to wrap my head around an animal so large being able to function with so little time taken in rest. Even though their physiology is clearly so different to that of a human, I still find it mind blowing that what I think is barely even enough time to close my eyes, a giraffe fits its entire day’s sleep into. Yet despite what we would consider an almost suicidal amount of awake time, giraffes continue to flourish.

And they never seem to be grumpy!

About the Author

Sean Zeederberg

Field Guide

As a young boy growing up on an agricultural farm in Zimbabwe, Sean spent every opportunity entertaining himself outdoors, camping in the local nature reserve and learning about all facets of the natural world. After completing a Bachelor of Science degree in Environmental ...

View Sean's profile

4 Comments

on A Not-So-Short Nap

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D. Phillips

Thank you so much for helping me learn something new each day. Very interesting.

Kim Drake

A fascinating read Sean, who would have thought a creature so large could function on so little sleep?

Darlene Knott

Interesting! Thanks for sharing!

Leonie De Young

Thanks for the very educational blog Sean. I would be unable to get by with so little sleep. Nature truly is fascinating. Thanks for the lesson.

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