I have not posted anything for a whole week, mostly because I have had to meet some deadlines at work. Apart from a pause from all social media and writing, deadlines have one other important effect on me: they disrupt my sleep. During these days, the mostly nonexistent sleep cycle that I imagine myself to possess suddenly vanishes.

This week, as I was falling asleep at my desk and making silly mistakes in my work, I started wondering if ants need to sleep too. This led to some intriguing reading through the night, and I feel like I can write a fairly interesting post on it. Fair warning: you should expect silly mistakes from my sleep-deprived brain.

So the question for this post is this: Do ants sleep?

First the short answer

Yes, ants do sleep. In an article published in 2009, entomologists (and a mathematician) from the United States showed that workers as well as queens in a fire ant colony slept in several short bouts through the day. This is called polyphasic sleep and if you have heard that geniuses use it, now you can add ants to the list.

Good night world! Ants sleep in several short episodes throught the day.
Source: pixabay

Fact to remember: It has not been established that polyphasic sleep makes you a genius, and the reverse is also not true.

What is this polyphasic sleep?

The word “polyphasic” uses the Greek-derived “poly”, which means “many” or “much” as in "polysyllabic "(okay, not a good example) and the word “phase”. It is basically sleep that you get in several phases. If you sleep for several short intervals through the day, that is an example of polyphasic sleep. That is the natural type of sleep for babies, and as we grow up, we gradually get rid of the several sleeping phases. We have mostly established the habit of sleeping through the night in one long unconscious slumber (or monophasic sleep), but some scientists think that the natural sleep in human beings could be biphasic. You know that time after lunch when you want to sleep at work? That could be because we are supposed to have two shorter periods of sleep rather than one long stretch during a 24 hour period.

Back to the fire ants

The number and duration of sleeping episodes of fire ants was not affected by the presence or absence of light.

One striking result from the study was that the sleeping habits of worker ants were very different from the sleeping habits of the queens. On average, the workers slept through 253 episodes during a 24 hour period, each episode lasting 1 minute 6 seconds. A worker would thus get sleep for 4.8 hours every day. The queens, on the other hand, had 92 episodes of 6 minutes each which gave them 9.4 hours of sleep in a day.

The sleeping episodes of the workers were not synchronized, meaning that all the workers did not fall asleep at the same time. This is important because someone needs to be awake and doing stuff in the nest after all. In contrast to this, the queens had synchronous sleep, which means that all the queens in the nest went to sleep together and woke up together. (Fire ant colonies have multiple queens; I should probably write about the politics in ant society soon.)

That royal sleep may be quite valuable, because fire ant workers have a lifespan that can be anywhere from 1 month to 1 year long and the queens live for 6 years. That is a big difference. The authors of the fire ant study think that the amount of sleep has something to do with the lifespan. They also cite an article that showed a very similar result with flies, meaning that flies that slept less died younger.

How do you know when ants are asleep?

Ants do not have eyelids and they probably do not snore, so if we want to make sure that they are asleep, we need to pay attention.

The researchers in the fire ant study used cameras to record videos of ants for a long time and when an ant retracted its antenna and was unresponsive to other ants, they called it sleep. It was certainly a moment of inactivity. Human and mammalian stages of wakefulness and sleep can be actually “measured” by using brain waves because the brain waves are different during waking hours and different phases of sleep (more on that later). But an ant has a group of nerve cell bodies called ganglion for its brain, and it is so small and the signals are so weak that we cannot measure the signals without changing the signals themselves. Tell me about the observer effect.

I mentioned that the queens apparently fall asleep at the same time and wake up together. They do this by physically huddling together when it is time to sleep. That way, if one of them wakes up, all the other queens also wake up.

Politics of royal sleep?

There could be biological reasons to it, but it made me wonder if there could be political reasons for it (I wonder if they are different?). Fair warning number 3: what follows is imagination and not science. Think about it. If a queen could wake up and find the other queens asleep, she might as well get her workers to make her the One Living Queen. Sleeping huddled together would certainly solve a problem of that nature. It is as if the queens have no secrets from one another.

Back to scientific scientific thinking! There could be ant species with multiple queens with unsynchronized sleeping patterns, and there could be other advantages to synchronized sleep among the queens.

Okay, do ants dream?

Yes, it does look like some of them do.

How do we know?

We need to start by looking at our own sleep and our own dreams. When we (or other mammals and birds) sleep, there are two distinct alternating modes of sleep called the REM sleep and the non-REM sleep. REM stands for “Rapid Eye Movement”, and as you can guess, REM sleep involves rapid movement of the eyes. This is the mode of sleep when we dream our dreams, and brain activity during REM sleep is very similar to the activity seen during our waking hours. And yes, that is why those nightmares are so scary.

Fun fact: the brain paralyzes your muscles during REM sleep so that you don’t actually fight those monsters in your dream and fall off your bed.

Non-REM sleep, on the other hand, is mostly dreamless and there is no rapid movement of the eye. (And no paralysis of the muscles. This is the time if you like sleepwalking.) So the point here is we can tell whether a person is in REM sleep or non-REM sleep by simply looking at him/her sleeping. The movement of the eyes would be a clue.

So what would we expect to see in a dreaming ant? We can’t see the movement of ant eyes, but the antenna could give us some information. Since it is the most important sensory organ for an ant, we can imagine that when an ant dreams, it dreams of perceiving the world through its antennae.

If we can assume that, at least the queen ants in the fire ant colony seem to dream stuff. They experienced two modes of sleep. During the light sleep, the ants dozed off and became inactive with their antennae stretched out, without any change from waking hours. They woke up easily from this state if they were touched by another ant.

The “deep sleep,” on the other hand, involved folding of the antennae to keep the world completely out. In this stage, the folded antennae were observed to quiver and twitch like they do during the waking hours when the ants are busy perceiving the world. The researchers concluded that this must be analogous to our REM sleep and named it the RAM sleep, which stands for Rapid Antennal Movement sleep. The RAM sleep seems to be limited to the queens only. In a fire ant colony, you have to be a queen to dream.

Why sleep when there is so much fun in the world to do?

When I was a kid, there was a time when I hated going to bed because I thought it was such a waste of time. I thought it unfair that the sun would disappear every night and make me go home to sleep when that time could be spent playing fun games with my friends. And when I grew up, I realized that I basically felt the same way, and because of the freedom of adulthood (read: mother not around to force me to sleep), I began staying up as long as I could.

Sleep is overrated! Worker ants seem to sleep much less than the queens, but that could be one reason that they die early.
Source: pixabay

I don’t know about you but quite a lot of people in the world seem to have serious problems with their sleep or sleeping schedules. We all understand how long we need to sleep to feel refreshed, but we do not seem to get enough sleep. We can guess that this causes some problems.

It has been shown that adequate sleep is important for a good memory and proper mental functioning, not only in human beings but also in honeybees. The researchers of the fire ant colony suggest that sleep might serve some similar purpose in the ant colony. They also suggest that the long life of the queens could be an effect of the better rest they get. And they mention that the workers appear to be disposable parts of the colony, working without rest to keep the queen healthy and happy, and then dying quickly.

Going back to our concept of the ant colony as a superorganism, finding an analogy for the asynchronous resting of different ants (i.e. organs) was a little difficult for me. Unless we think of actions such as “resting our eyes,” all our organs seem to sleep together. We could probably look at animals that sleep with only half of their brain at a time. (And yes, they close only one eye when they are asleep.)

Can you think of any organ in an animal or plant body that works hard without rest and dies quickly in order to keep some other special organ safe? Does the brain qualify to be the special organ? Let me know in the comments! And sleep well.

Links to references and image sources are provided in the text.