Do Flies Sleep? Where Do Flies Go At Night?

Last Updated on: January 26th, 2021 at 3:20 pm

Around a decade back, researchers at the University of Queensland conducted a study on flies to study their ability to sleep.

The study was conducted by Associate Professor Bruno van Swinderen. The study clearly stated that – Flies do sleep.

Apart from this, the study also suggested that the sleeping cycle in flies is very much similar to humans.

Human sleep involves two stages:

  1. Rapid eye movement (REM) stage, also known as the light sleep (during which we can see dreams)
  2. Non- REM stage, also known as deep sleep

Similarly, the fly sleep cycle also consists of two stages i.e. the light sleep and the deep sleep. This study established a ground-breaking fact that even the smallest animal brains need sleep to work properly.

Where Do Flies Go At Night? Do Flies Sleep At Night?


Most species of flies (including house flies, bottle flies, flesh flies etc.) are active during the day and become inactive during the night. These species of flies need polarized light to guide them visually. Apart from this, at night the temperature is a bit lower and this makes them slow and lazy.

So, as the day comes to an end, flies take refuge under leaves or grasses, on the branches, or on tree trunks. Then these flies sleep there till the sun rises again. They don’t have a nest, a colony, or anything. They just find a place to land and rest. This could be anywhere.

This is what most species of flies do at night. However, there are a few exceptions like Sand Flies and Fruit Flies which mostly prefer relatively cooler climate and hence are most active during dawn and dusk.

Where Do Flies Sleep?

Flies mostly sleep during night time however sometimes they also take short naps during day time.

Generally, flies do not search for sleeping areas that are predator free, but instead they just sleep anywhere. Flies can be found sleeping on floor, walls, curtains, plant leaves etc.

Interesting Facts About Fly Sleep:

Here are some interesting facts about fly sleep:

  1. Flies get most of their daily required sleep during the night. However, they also take few short naps during the day.
  2. The sleep cycle of a fly is affected in the same way by certain drugs, as it does for the humans. For example: chemicals like caffeine, cocaine and modafinil (a medicinal component that keeps humans alert) keep flies awake. While Antihistamines or alcoholic beverages make them drowsy just like humans.
  3. Flies need more sleep in hot climates than in slightly cooler climates.
  4. If flies are not allowed to, sleep peacefully for a night, they’ll try to sleep more the next day to make up for it. This is called sleep rebound.
  5. Increased sleep deprivation in flies can even effect their memory.
  6. In another study, researchers found that baby flies need more sleep than adult flies. Baby flies require more sleep for brain development.

Genetic Changes and Their Effects on Fly Sleep:

Experiment 1:

In 2008, the Seghal lab at the University of Pennsylvania tried to identify the sleep-related genes in flies. For this, they performed a genetic screening in which they exposed a population of flies to toxic chemicals.

These chemicals caused random genetic mutations in those flies. After this, they checked these flies to see if any of the flies have developed sleep abnormalities.

They found that flies with a mutation in one gene (which they later named as SLEEPLESS GENE) were sleeping almost 80% less than any average fly.

For more details please see the link at the bottom of the article.

Experiment 2:

In another experiment conducted the very same year at Guo labs, it was established that in flies sleep is related to memory.

Here the researchers mutated some set of genes in the flies that affected their memories. The mutated flies were called amnesiac fly mutants. The amnesiac mutants were not able to have long term memories. Apart from that they also had a fragmented sleep (meaning that they woke up a lot during the night).

This research helped scientists to connect the dots between sleep and memory.

For more details on both the experiments, you can check out the following article:

So, this was all about flies and their sleeping cycles. Check out other interesting articles below:

About Ankit Zadi

My name is Ankit Zadi, and I can call myself a 'Fly Expert'. My adventures with flies began when we shifted to our new house seven years back. My goal on this website is to share everything that I know about flies. Check out my full story here.