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?

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    $\begingroup$ related: biology.stackexchange.com/questions/19176/… $\endgroup$ Sep 9 '14 at 12:59
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    $\begingroup$ What happened to the purpose of sleep as a mechanism of physical relaxation? After a hard day's work, they would need to relax. $\endgroup$
    – ontherocks
    Sep 9 '14 at 16:05
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    $\begingroup$ "act more as a collective than an individual" That's just perspective, same can be said for humans. $\endgroup$
    – Jonathan
    Sep 9 '14 at 17:57
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    $\begingroup$ @Jonathan Yeah I completely agree, I meant more of a collective intelligence. Badly worded :p $\endgroup$
    – J_mie6
    Sep 9 '14 at 18:18
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    $\begingroup$ Sleep can have many uses, and may have different uses for different species. NIH claims that sleep may be used also to help remove toxins from the brain, which would be beneficial for ants, too. $\endgroup$ Sep 9 '14 at 19:12

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.

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    $\begingroup$ Interesting, a queen gets 9 hours of sleep, a worker only 4.5 hours... $\endgroup$
    – yo'
    Sep 9 '14 at 13:37
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    $\begingroup$ @tohecz: also queens sleeps are much longer & less interrupted -> more quality sleep time. $\endgroup$ Sep 10 '14 at 7:10
  • $\begingroup$ Are there animals that don't need sleep? $\endgroup$
    – Tim
    Sep 12 '14 at 2:16

The short answer is apparently yes. Studies on sleep in insects date back to papers published by Phil and Nellie Rau in 1916 and 1938. Hussaini et al. (2003) showed that sleep does affect memory formation in honey bees. They showed that retention of extinction learning is significantly reduced in bees that were sleep-deprived. More about sleep in honeybees can be found in this paper by Eban-Rothschild and Block (2012).

I did not find anything on sleeping in ants after a brief Google Scholar search but ants and bees are both hymenopterans, so it's reasonable to hypothesize that many of the effects of sleep (and sleep deprivation) found in bees could also apply to ants. The Eban-Rothschild and Block paper linked above has some comparisons of circadian rhythms between ants and bees before discussing sleep as a function of circadian rhythms.


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