Do Flies Sleep?

Have you ever wondered where flies go at night, do they sleep like humans?

Most flies sleep in the night; however, they sometimes also take short naps during the daytime. Rest is a vital part of the daily life of any living thing. Even the smallest brains need sleep to work properly. 

Read on for more information on when and where flies sleep.

What Are Flies?

Globally, there are more than 120,000 species of flies. So a better heading for this section might be “what kinds of flies are there.” 

fruit fly sleeping at night

Too many!

Flies typically have a short life span between 5 – 30 days. The most common types of flies include gnats, midges, mosquitoes, houseflies, drain, horse and fruit flies.

Where Do Flies Go at Night? 

Most flies, with the notable exception of mosquitoes, are daytime fliers. 

They require polarized light to guide them visually. They remain active during the day and become inactive during the night.

Flies are cold-blooded, meaning that their temperature is similar to that of their surroundings. Most flies do not develop or function well at low temperatures. 

The night temperature is low as such, it slows them down and makes them lazy. If it’s freezing, most go into a dormant state, where body functions are significantly slowed.

sleeping fly

When night falls, most flies take refuge. 

They find a place to land and rest till the sun rises again. Sites to rest include, under leaves or grass, on branches, tree trunks, walls, curtains, corners, flat surfaces, bath stalls and so on. They really can sleep anywhere.

Do Flies Sleep?

The answer is yes. 

Flies have a central nervous system, which is an essential characteristic of sleep. They also have circadian behaviors that govern when they sleep and wake up.

Humans sleep in two stages, the rapid eye movement stage (REM) and the non-REM stage. These stages are also referred to as light and deep sleep. Similar to humans, studies have shown that sleep in flies also alternates between stages of lighter and deeper sleep. They also established that even the smallest of brains need rest to work!  

sleeping human compared to flies

Interesting facts about sleeping flies  include:

  • While most sleep at night, they sometimes take short naps during the day.
  • Just like humans, flies sleep is affected by certain drugs and chemicals. For example, caffeine and cocaine keep flies awake while antihistamines and alcoholic beverages make them drowsy, just like humans.
  • Baby flies sleep more than adult flies for normal brain development.
  • They sleep more at higher temperatures.
  • Sleep deprivation affects memory performance. Hence, if flies don’t get a good night’s sleep, they tend to sleep more the next day to make up for it, just like humans!

How Long Do Flies sleep?

Most flies get most of their sleep during the night. Ideally, a fly can sleep for 12 hours.

Do Flies Sleep in the Dark?

Flies generally prefer warm weather and sun. Hence, they are active during the day, looking for food and rest when the sun goes down. 

Exceptions like sand flies and fruit flies prefer relatively cooler environments. They are most active during early morning hours and in the evenings.

Other flies like the mosquito that stay up at night looking for food. They have adapted their super-sensitive eyes and antennae to see in the dark. They rest and sleep during the day.

clock and flies sleeping

Flies can sleep both during the day and at night; being dark is not a prerequisite.

Can You Get Rid of Flies at Night?

Spraying the common resting areas with insecticides will ensure that flies that rest on the sprayed surfaces die. Light traps also work best at night since the flies will be attracted to the light.


Just like humans, flies need sleep. Baby flies need more sleep than adults to develop and grow. So, why should you care about flies sleep? 

Studying the flies’ sleep cycles can give you insight into their behavior, from relevant molecular pathways to the genes involved. It also offers insights on better ways to control pests, including times of day when pesticides can work better.