Subscribe now


Half Asleep

Sat May 02 03:25:02 BST 2009 by Galaxiom

Sleeping half the brain at a time is quite common in the animal kingdom. Watch ducks for a bit and you will see them stand on one leg with one eye shut while they half sleep.

Our inability to do it is just another in a substantial list of anatomical features that humans missed out on in evolution's lottery.

Half Asleep

Mon May 04 03:39:36 BST 2009 by Dann

Human ancestors probably never had the need to be conscious 24 hours a day. Since our night vision is practically non-existant (compared to that of owls or cats, for instance), our ancestors would have seen little benefit in staying awake at nights. Especially before hominins learned to create or use fire.

If there are many hours each night when you really can't go out and do anything useful, you might as well spend them in a deep sleep. That way you can stay constantly awake and fully alert during the day.

Sleeping with half the brain at a time is often an adaptation seen in air-breathing aquatic animals. Cetaceans don't have a breathing reflex, so they need to be partially conscious all the time otherwise they stop breathing. Birds that sometimes sleep on open water (like ducks) need to be semi-alert to prevent themselves from drifting towards shore and coming into the reach of terrestrial predators.

Half Asleep

Fri May 08 13:43:22 BST 2009 by Kevin

I wouldn't say we missed out on it, we simply didn't have the evolutionary pressure to make it a genetically important trait. Instead we can ask someone else to keep an eye out while we sleep, or if alone we can arrange to sleep after setting traps and alarms to warn us of approaching predators (or we can simply find or create a safe place).




Latest news articles

Virtual reality: It's time for garage inventors again

21:00 19 June 2013


Inside Fukushima: Draining a radioactive flood

20:30 19 June 2013


The battle to find a cure for every cancer is evolving

20:00 19 June 2013


Dreams on demand: Virtual reality finally delivers

18:53 19 June 2013



© Copyright Reed Business Information Ltd.