I was thinking yesterday about insects (as there was a spider in the house, and I couldn't help but think of anything else, even though they aren't insects), and I started to wonder if ants sleep? 

After thinking about it for a while I decided that they might sleep, but then what would be the purpose of sleeping for them? My limited understanding of the need of sleep is that it is used for the brain to compartmentalise the events of the day and allow memories to be formed. But ants don't really have to think about much during the day, given that they act more as a collective than an individual. Or in the case of other insects, they have simpler more instinctive brains which rely on taxis, reflexes and kineses. 

So, do ants and other insects sleep (or do they have a different type of sleep to us) and what would the purpose of it be for them?

A quick search on Web of Science yields "Polyphasic Wake/Sleep Episodes in the Fire Ant, Solenopsis Invicta" (Cassill et al., 2009, @Mike Taylor found an accessable copy here) as one of the first hits. 

The main points from the abstract:


Yes, ants sleep.
indicators of deep sleep: 

ants are non-responsive to contact by other ants and antennae are folded
rapid antennal movement (RAM sleep)

Queens have about 92 sleep episodes per day, each 6 minutes long.
Queens synchronize their wake/sleep cycles.
Workers have about 253 sleep episodes per day, each 1.1 minutes long.
"Activity episodes were unaffected by light/dark periods."


If you study the paper you might find more information in its introduction or in the references regarding why ants sleep, although there doesn't seem to be scientific consens. The abstract only says that the shorter total sleeping time of the workers is likely related to them being disposable.
