Giraffe Sleep

[Northern_Piper]

@kayT

Maybe our own Giraffe will be along to answer. When he wakes up.

♫ Where’s Jeff? ♫

♬ Is he sleeping outside? ♬

♫ Where’s Jeff? ♫

♬ Has he gone for a ride? ♬
[Yes, the Piper Cub has discovered the Wiggles - why do you ask? ]

[blondebear]

One interesting (but non-sleep related) thing about giraffes is that they avoid any kind of uneven terrain. That’s why they can be kept in enclosures with what seem to be ridiciously shallow moats. A keeper told me that they won’t even walk on cement that has been sprinkled with water because they see the wet spots as holes in the ground.

[TriPolar]

@Mijin

Agreed.

One theory on sleep is that it keeps organisms out of danger. e.g. Humans have specialised for daytime activity, so we sleep at night to keep us from wandering about at a time when we can’t effectively do anything (sans lightbulbs).
The main problem with this theory is why we go into a deep sleep and not into an alert but resting state, which would be much safer.

But it occurs to me that the situation with giraffes presents a much more difficult problem to explain from this perspective, and may destroy the theory outright.

The giraffe is a riddle, wrapped in a mystery, inside an enigma, with a very long neck. I suppose in the case of sleep, the giraffe has managed to adapt to the minimal amount of sleep necessary. Perhaps with less sleep the giraffe becomes inattentive and prone to predation or injury. Or there may not be advantage to giraffes sleeping less than they do.

Another possibility could be related to their complex cardio-pulmonary system. Numerous adaptaions allow a giraffe to keep it’s brain so far above it’s heart. If sleep reduces heart rate and blood pressure, it may interfere with the process. I assume that’s one reason giraffes bend their necks back over their body or onto the ground while sleeping, so that the brain could be kept oxygenated with lower blood flow.

On the other hand, maybe giraffes descended from some a single animal with chronic insomnia. Maybe like me, they wish they could get more sleep.