How Do Bed Bugs Know When You Are Asleep

Do Bed Bugs Know When You’re Asleep or Awake?

Bed bugs are sneaky parasitic creatures that aren’t often seen during the day. Instead, they come out at night, while we’re asleep. This gives them the chance to feed without interruption. When it’s light, they hide away in harborages around the bedroom.

Bed bugs just know that night time (when it’s dark) is when humans are most likely to be inactive. Bed bugs can smell the carbon dioxide that we give off while we’re in bed, so that’s when they emerge to feed. The light will deter bed bugs from coming out, but not for very long.

We’ll look at why bed bugs come out at night, and whether it’s true that they only bite humans while we’re asleep. We’ll discuss whether you can deter bed bugs by sleeping with the light on. Finally, we’ll share some tips for sleeping with bed bugs, and ways of repelling them.

Table of Contents:

Why Do Bed Bugs Come Out at Night?

If you have bed bugs, you’ll know that they usually come out at night. They make themselves comfortable in mattresses, headboards and box springs, and rest during the day.

Bed bugs have to drink human blood, to survive. So, when your head hits the pillow at night, they come out to feast. In the morning (or several days later, depending on how your body reacts) you wake up with itchy bite marks.

So,why do bed bugs avoid light, and come out at night? Bed bugs are different from other parasites. Unlike fleas,ticks, andlice, they can’t live on our bodies full-time.

Their legs aren’t designed for clinging onto skin or hair. As we walk around, bed bugs get dislodged and end up falling off. The most they can manage it to climb on, feed, and then leave again.

This is why they choose tofeed while we’re asleep. Every night, we lie down in bed and remain still for around eight hours. Bed bugs smell the carbon dioxide that we exhale, and come out to feed. We sometimes squash them when we roll over in our sleep, but the risk is minimal for them.

Bed bugs have learned to associate light with humans being awake and moving around. So, they wait until darkness falls before coming out of hiding.

Do Bed Bugs Only Bite When You Are Sleeping?

One of the commonmisconceptions about bed bugsis that they’ll only bite when you’re asleep.

It’s easy to tell where this myth came from. As we know, bed bugs prefer to avoid light, and of course, they chiefly live in beds. We don’t tend to spend much time in our beds unless we’re asleep. However, that does not mean that bed bugsonlybite you when you’re sleeping.

Bed bugs can’t tell when a human is awake or asleep. As long as you are staying relatively still, you’re fair game to a bed bug. You can be bitten when you’re relaxing on the couch, for example.

If you have a home office, this is another prime bed bug spot. Bed bugs can live inside office chairs and electronics. There was even a case of bed bugs living inside a woman’s mouse mat. They bit her hand every time she used the computer.

So, while bed bugs do prefer to feed on a sleeping host, any period of inactivity will do. As long as you remain still long enough for a bed bug to feed.

Do Bed Bugs Come Out in the Light?

Bed bugs don’t like the light very much. This is obvious. Even in a heavily infested home, you probably won’t see many bed bugs moving around during the day.

Because of this, you may be wondering: are bed bugs light sensitive? Does the light hurt bed bugs in any way?

Unfortunately, no, it does not. Bed bugs may have an aversion to light, but it’s not because light harms them.

It’s merely because bed bugs are naturally nocturnal. The presence of light indicates that it’s the day time, which is when they rest.

Why are bed bugs nocturnal? Because humans aren’t. When we’re sleeping, we’re the perfect target. We generally don’t move much during the night. So, there’s less chance we’ll (accidentally or deliberately) jostle the bed bug while it’s feeding.

Electric lights fool bed bugs into thinking that it’s day time. They’re less likely to come out when we have a light on.

You can test this for yourself. Lie down in bed with the lights off, and wait for an hour. Then, switch the lights on. Chances are, you’ll see at least a few bed bugs scurrying away to hide.

Can Sleeping With the Lights On Deter Bed Bugs?

If bed bugs have an aversion to light, does that mean they’ll stay away if you sleep with the light on?

Unfortunately, if you want to deter bed bugs sleeping with lights on won’t help much. By all means, you can try it. Just don’t expect it to work for more than a couple of days.

Why doesn’t it work? Well, sleeping with the lights on will fool bed bugs (at first) into thinking it’s daytime. They’ll stay hidden until the lights go out. However, it can’t fool them for very long.

Sooner or later they’re going to get very hungry. Bed bugs can survive for months without a meal, but they don’t like to. They prefer to feed at least once a week if possible.

If they detect that you’re nearby, they’ll eventually come out and feed whether the lights are on or not. It’s as simple as that.

Tips for Sleeping with Bed Bugs

It can be challenging to get a good night’s sleep if your home is infested with bed bugs.

Falling asleep knowing that you’re moments away from having your blood sucked by insects isn’t easy. It causes very real anxiety and paranoia in most people.

So, here are some tips to help you sleep, knowing that your bed is playing host to parasites:

  • Relax in the evenings. Take a long, warm bath and read an old favorite book, for example.
  • Drink chamomile tea about an hour before bed. Not only does it help you fall asleep, but it also helps improve sleep quality.
  • Fall asleep while listening to soothing instrumental music, an audiobook, or a podcast. This will help to distract and ease your mind.
  • Take natural sleep aids, such as melatonin. If you are experiencing severe sleep deprivation, talk to your doctor about prescription sleeping pills.

You may be tempted to sleep in a different room – on the couch, for instance. However, it’s not a good solution. Changing where you sleep may distract the bugs for a few days, but they will eventually find you again. Bed bugs can smell the carbon dioxide that your body emits.

Likewise, you may also consider covering as much of your body as possible in bed, to give the bed bugs less access to skin. However, if you do this, the bed bugs willbite an area which isn’t covered by your pajamas– such as your face.

Can You Stop Bed Bugs From Biting at Night?

Unfortunately, if your home is infested with bed bugs, there’s almost nothing you can do to stop them biting.

Bed bugs need to drink human blood to survive, and they have a powerful will to live. If they can physically reach you, they will find you, and they will feed.

If you can’t get rid of the infestation completely, you can try to bed-bug-proof your bed. There are three main steps:

  1. Install a mattress encasement. These are like huge, zip-up bags that you place your mattress inside. They are designed to have no gaps, so that bed bugs cannot escape. Existing bed bugs get sealed inside, and can’t get to you. Eventually, they starve to death.
  2. Move your bed away from the wall and the window. This way, new bed bugs won’t be able to climb the walls orcurtainsto reach your bed.
  3. Install bed bug interceptor traps under the legs of your bed. These are designed to trap bed bugs when they try to climb up your bed legs.

If you follow the above steps, your bed should be safe. Unfortunately, they may still bite you in other areas of the home.

What Else Do Bed Bugs Dislike?

So, to summarize what we’ve learned, bed bugs don’t like the light. They prefer to come out when it’s dark, as there’s a better chance that we’ll be asleep.

However, switching on the light at night won’t deter bed bugs for very long. And while you can protect your bed if you’re through, the bugs will still exist in other parts of the home.

So, is there anything else that will repel bed bugs?

Extreme Temperatures

Bed bugs have adapted to live at the same temperatures as humans. They’re most comfortable at typical room temperatures of between 65 and 85 degrees Fahrenheit.

Both extreme cold and extreme heat can be fatal to bed bugs. However, they can survive easier in cold temperatures than hot ones. Unless the temperature is lower than 0 degrees Fahrenheit for at least four days, some bed bugs will survive.

Creating a sub-zero environment in your own home is hard. However, you can use heat to your advantage. Hand-held steam cleaners can deliver fatal blasts of scalding steam to beds, couches, and carpets. You can also launder your bedsheets at 140 degrees Fahrenheit to kill all bugs and eggs.


Insecticides, like pyrethroids, are somewhat effective at deterring bed bugs. They are poisonous to insects, so they will kill bed bugs upon contact. Most insecticides are sold in liquid form. You can brush them on, or spray them around the home.

The only trouble is that in recent years, some strains of bed bugs have developed a resistance to insecticides. There’s no guarantee that they will work for the specific bugs in your home. If you’d like to give pesticides a go, try buying a small bottle first to test it out.

Essential Oils, Alcohol, and Vinegar

There is some evidence that bed bugs are repelled by vinegar, alcohol, and essential oils. It’s likely that you’ll have some of these around the home anyway, so they’re worth a try.

Tea tree oil is effective against bed bugs, compared to other essential oils. It has a strong smell which bed bugs don’t like. If it actually touches a bed bug, it’s fatal. It’s not effective if diluted, though. Undiluted tea tree oil can also be harmful to humans and pets.

High-strength cleaning vinegar also repels bed bugs, and kills them on contact. It’s irritating to the skin, so wear gloves when using it. Unfortunately, it has a strong, unpleasant smell that lingers.

If you choose to use alcohol, you’ll need to opt for rubbing alcohol rather than drinking alcohol. It’s only about 50% effective at killing bugs, but it does repel them reasonably well.

Diatomaceous Earth

Diatomaceous earth is a sedimentary rock, sold as a white, talc-like powder. You can buy food-grade diatomaceous earth, which is safe to use around pets and children.

It’s a desiccant, which is the technical term for a drying agent. The small, sharp particles make tiny cuts in the waxy coating on a bed bug’s shell. The moisture inside evaporates, and is absorbed by the diatomaceous earth. Eventually, the bed bug dehydrates and dies.

Bed bugs can’t become resistant to diatomaceous earth. They will avoid it at all costs. Apply it to any area of the home that you think may harbor bed bugs.

Light Colors

Though it may sound strange, bed bugs have a preference for certain colors.

According to a study in theJournal of Medical Entomology, bed bugs actively avoid harborages (hiding places) that are yellow or green. Theyprefer darker colors, such as red, black and purple.

Unfortunately, buying yellow bedsheets isn’t enough to get rid of a bed bug infestation. It will, at best, put them off for a few days. If a bed bug is at risk of starving, they’ll find you and feed.

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Lou Carter

Hi, I’m Lou. I’ve long been fascinated by bed bugs, ever since a friend’s life was turned upside down. That’s why I’ve put together this specialist site. You’ll find detailed answers to all of your questions on how to get rid of a bed bug infestation. I hope you find it useful!

How Do You Know If You Have Bed Bugs?

Signs of a bed bug infestation include live bugs, rust-colored spots on bedding, shed exoskeletons and a musty color.People sleeping in an infested room develop bite marks, but these sometimes take up to two weeks to appear.

Most people are unaware they are being bitten by a bed bug. The bugs normally bite while the individual is asleep. They inject an anticoagulant that allows them to feed freely on the victim’s blood. The bug also injects an anesthetic so the sleeping individual does not feel the bite. The skin reaction to bed bug bites depends on the individual’s allergy levels. Some people develop no reaction at all, while others experience anaphylactic shock. However, red, itchy spots that resemble mosquito bites are common.

Anyone who visits an area infested with bed bugs is at risk for bringing an infestation to his own home. Bed bugs often transfer to the luggage or clothing of humans in hotel rooms and other places where people share living or sleeping areas previously used by others. Bed bugs have slim bodies and often move from one location to another without detection. Once the bugs infest an area, they are difficult to eradicate. Getting rid of them often requires the services of a professional exterminator.

ELI5: How do bedbugs know you’re asleep and then come out to bite you?

ELI5: How do bedbugs know you’re asleep and then come out to bite you?

They sense the heat off of your body when you lay down at night. There’s a cool/disturbing YouTube vid I watched where they took a hair dryer and the bed bugs went crazy.

They don’t. They know that you are in the bed through movement, scent, and the CO2 you breathe out. They do not wait till you are asleep to come feed if they are hungry and you are there.

To my knowledge, most bloodsucking insects/arachnids are drawn to carbon dioxide. You also produce more co2 when asleep, which is why they eat you while sleeping. Also, unlike other pests, bedbugs feed directly on blood. This eliminates the need for dirty living quarters for an infestation to happen. They don’t eat rotten food, fecal matter, etc.

They don’t give a fuck what time it is. If you don’t keep your sheets clean, the little bastards will eat you any time of day.

Yeah but apparently they’re hard to catch because they don’t come out when you’re actively looking for them. Also he cleanliness thing is a myth. They don’t care how hygienic you are; they will hide anywhere.

Keeping your sheets clean has nothing to do with bed bugs

What Do Bed Bug Bites Look Like? Here’s Exactly How to Spot the Symptoms

If you wake up with a line of three to four itchy, swollen bumps, it could be due to bed bugs.

Waking up with a fresh set of itchy bug bites can bring on its own set of worries. What, exactly, was biting you in the middle of the night? Was it a spider? Mosquito? Or—possibly theworstcase scenario—could it have been bed bugs?

Although bed bugs might not be the first thing we think of when we wake up with a bite, the crittersdoget their food source from our blood—and will leave a little red bump in their wake after getting their fill.

But the trouble with identifying a bed bug bite—as is true for a lot of insects, including mosquitoes—is that it can be hard to identify the source of the bite, as everyone reacts differently to being bitten based on what their body’s immune response is. “Everybody’s going to respond differently,” saysTimothy Gibb, PhD, a clinical professor of entomology at Purdue University. “Same thing’s true with a mosquito bite. Some people are going to swell up and it’s going to itch. That same mosquito could bite someone else and it’s hardly noticeable.”

In fact, Gibb says some people may have no response when being bitten by a bed bug at all, based solely on how their immune system handles the bite. That’s why it can be difficult to determine whether your bite is the result of a bed bug just by looking at it.

But therearea few things that can tip you off to the fact that bed bugs are the culprit of your bites. Here’s what to know, including bed bug bites pictures to help you visualize the symptoms.

What do bed bug bites look like?

The key bed bug bite symptom to look for is a red, raised bump, says Gibb, similar in appearance to what you would get when bitten by a spider or a mosquito. But what sets bed bugs apart from other insects is that oftentimes,their bites will present in a line on one part or side of your body. This is the result of what’s called “probing.”

⚠️ Bed bug bites show up in a line, most often in a cluster of 3 to 4 bites.

“They probe the skin in several different places, I think probably to find best access to draw blood,” says Gibb. In fact, if you have screens on your windows—thereby keeping out other insects that might bite—but are still waking up with aline of 3 or 4 bites on your arm, it’s safe to suspect that bed bugs might be to blame, saysEdwin Rajotte, PhD, a professor of entomology at Penn State University.

Another way to determine if your bites are a result from bed bugs is to look for the insects themselves. They naturally like to hide in on your mattress, especially in the corners, near the head end, and in the cord that goes around it. They also like to camp out behind the headboard, behind any pictures on the wall, and in any electrical sockets.

Adult bed bugs are about the the size of an apple seed and are very flat from top to bottom—almost as thin as a piece of paper—with a brownish color, says Rajotte. Baby bed bugs are also brownish in color, but pinhead-sized. Another key identifier? Look for black spots on your sheets, mattress, and mattress cover, which could be bed bug feces.

Where do bed bugs bite, exactly?

Bed bug bites willmost commonly occur on the arms, neck, or trunk of the body, says Gibb, although they’ll bite anywhere they can find exposed skin. And—as their name suggests—bed bugs will bite you at night while you’re sound asleep.

“We’ve found it’s most active when people are most sound asleep, and that’s usually from about 2:00 to 4:00 in the morning,” says Gibb. “That’s natural for a parasite like that to do that because it’s going to protect it. People won’t see it, they won’t feel it. It makes their survivorship much more probable.”

Are bed bug bites itchy? Do they hurt?

Although some people will say a bed bug bite hurts somewhat—though not as intensely as the sting of a bee, for example—most complaints are due to the itching the bites cause, says Gibb. And that itching is due to the chemicals the bed bug inserts into your body during the bite, adds Rajotte.

“They’ve become what I consider the perfect parasite, because their mouthparts are kind of interesting,” says Gibb. “They will inject an anesthetic prior to biting, so people won’t feel it. And then they inject an anticoagulant that allows the blood to run easier for them to suck that up.” So while that system works great for thebugs, those left-over chemicals will usually lead to some uncomfortable itching on your end.

How long do bed bug bites last?

Although the duration and intensity of a bed bug bite will hugely vary from person to person, you typically won’t feel the effects of a bed bug bite—like itching and those raised red bumps—until mid-morning after a bite due to the anesthetic the bug injects, says Gibb. “So they certainly don’t feel it when the bite is occurring, but shortly after, probably within a day, for sure,” he adds.

From there, a bed bug bite will stay with you for typically at least 24 hours, though theycould last three to five days after the initial bite, says Gibb. At that point, the bite will then start to slowly dissipate.

How to treat bed bug bites

If you’ve received a bed bug bite (and the itching that comes along with it), chances are, you’re going to want to speed up the treatment process. But unfortunately, the best way to do that is also thehardestway to do it: not scratching the bite, says Gibb, which will just further irritate the area.

If you’re having trouble keeping your fingers away from the bite, you can also try using an antihistamine—think Benadryl or Allegra, which are meant to curb allergy symptoms—to help mute that itchy feeling.

And if bed bugsarethe cause of your bites, realize there’s no urgent need to panic. Yes, they might cost you a pretty penny and can be a pain to get rid of, but bed bugs can’t do any serious damage to your body.“They don’t kill people,” says Gibb. “A parasite would have a hard time surviving if it killed its host, and these do not.”

In fact, they don’t even transmit anything dangerous to you.“They’ve never been shown to transmit any diseases,”says Rajotte. “Unlike mosquitoes and ticks and things, which can transmit some pretty bad diseases, bed bugs do not. And so while they’re annoying and all that, they’re not going to harm your children or anything like that. They’re just annoying and you need to get rid of them.”

Ready to banish them from your home? Here’s our expert-approved, step-by-step guide to getting rid of bed bugs for good.

Bed bug bites: What you need to know

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Most people who are bitten by bed bugs experience symptoms that include irritation, sores, or itchiness. But how should bed bug bites be treated and can they be prevented?

There are several ways of reducing the chances of getting bites, while the treatment options include good hygiene and antihistamines.

This article explores bed bug bite treatment and prevention methods in detail.

Bed bugs are small parasitic insects that feed on human blood.

While they are a public health concern, bed bugs are not known to transmit disease through their bites.

Bed bugs use a small tube-like structure called a proboscis to pierce the skin and drink a person’s blood. The pests are most active when humans are asleep, during the night and early morning.

An estimated one in five Americans have personally dealt with a bed bug infestation or knows someone who has encountered the pests.

Bed bugs can bite anywhere on the body where there is skin. Typically, bites tend to occur on areas exposed during sleeping, such as:

Many people do not feel the bite itself or develop clear symptoms other than the dots where the bug bit and some minor, surrounding inflammation and irritation. Others are considered hypersensitive to bites and develop more severe symptoms.

In most cases symptoms occur more or less immediately after the bite, but they can develop or progress over the following days as well. Without further irritation, symptoms typically resolve after a week or so.

Almost all bed bug bites will produce some degree of discomfort, typically itchiness and inflammation. Other signs and symptoms of bed bug bites include:

  • a burning painful sensation
  • a raised itchy bump with a clear center
  • a red itchy bump with a dark center and lighter swollen surrounding area
  • small red bumps or welts in a zigzag pattern or a line
  • small red bumps surrounded by blisters or hives
  • papular eruptions or areas of skin with raised or flat patches that may be inflamed
  • small spots of blood from bites often dried or stained onto sheets or bed clothing
  • reddish or reddish-brown dried stains on fabrics due to bed bug droppings
  • white or clear skins, shed by the nymphs as they mature

Individual characteristics of the bug’s bite and the person who is bitten also influence the resulting sore.

While fairly rare, some people have or develop severe reactions and symptoms from bed bug bites. Serious symptoms that require medical attention include:

  • difficulty breathing
  • blisters
  • fever
  • feeling nauseous or flu-like
  • swollen tongue
  • irregular heartbeat

Living with bed bugs can cause additional health complications:

  • Increased likelihood of infection: Due to the skin’s surface being compromised.
  • Sleep deprivation: The idea of being fed on can be extremely stressful. Given that the bugs only feed at night, some people will avoid sleep or will only get fitful or restless sleep.
  • Decreased wellbeing: A continual lack of sleep has been linked to feelings of depression, anxiety, general fatigue, and lowered immune function. The misconceptions surrounding bed bugs, especially the mistaken association with lack of cleanliness, can add to feelings of depression and low self-esteem.

There are relatively few treatments options when it comes to uncomplicated bed bug bites.

The first recommended line of treatment involves cleaning the wound, ideally with soap and water.

For itchy bites, the following may relieve minor symptoms:

  • over-the-counter hydrocortisone, which can be purchased online.
  • anti-itch creams
  • antihistamines

Most wounds heal on their own within a week, sometimes two.

If severe swelling, inflammation, or itchiness occurs or persists, a person should seek medical attention.

A dramatic immune response may be a sign of an allergic reaction. If this is the case, one of the following may need to be administered:

  • an injectable corticosteroid
  • antihistamine
  • epinephrine medication

If infection occurs, antibiotics may be prescribed.

Severe itchiness may result in further complications, such as infection or scarring. If severe itching is experienced, people may be prescribed corticosteroid creams and antihistamine pills or liquid.

One way to help prevent exposure and potential infestations by bed bugs is to be able to recognize bed bugs and distinguish them from other pests.

In a 2017 study, some 35 percent of polled American business travellers and 28 percent of leisure travellers were unable to tell a bed bug apart from other household pests.

Common characteristics of nymphs (young bed bugs) include:

  • being less than than 5 mm in length
  • whitish-yellow and or clear-colored
  • invisible without a microscope or magnifying glass

The nymphs are easier to see if they have just feed when the blood fills their abdomen, giving it a reddish brown color.

Adult bed bugs are typically far easier to spot than nymphs. Identifiable characteristics of most adult bed bugs include:

  • an oval-shaped body
  • apple seed in size
  • a body that is fairly flat unless recently fed and inflated
  • reddish-brown to light-brown or tan color of shell, depending on how recently it fed
  • a length of 5-7 millimeters (mm)
  • three segments, an antenna with four parts, short yellow hairs, and unusable wings
  • a musty or stale-sweet scent released by glands on the underbelly

Controlling bed bugs needs the identification and complete removal or destruction of the pest’s eggs.

On average, one female can produce at least 345 eggs over her lifetime. Egg-laying females often increase the volume and frequency of feeding to support their brood.

Common characteristics and signs of bed bug eggs include:

  • they are often laid in the same places where the female choses to rest
  • they resemble tiny barrel-shaped, pearl-colored specks, no bigger than the head of a pin
  • they develop a noticeable eye spot after a few days

The key to preventing bed bug bites is to stop the insects entering, feeding, and breeding in human environments.

In the daytime, bed bugs often seek refuge in the cracks and crevices of furniture, flooring, walls, and mattresses.

The seams and folds of upholstered furniture can also offer an ideal hiding place. Bed bugs have been known to persist in vacuum canisters or units.

The insects tend to pick hiding spots near human sleeping quarters, including bedrooms. Bed bugs found in other rooms are usually a sign of a severe infestation.

Areas where bed bug infestations commonly occur include:

  • apartment or condominium buildings
  • large office spaces
  • hotels
  • vacation rentals
  • cruise ships
  • daycares
  • nursing homes
  • hospitals
  • college dormitories or housing units
  • public transportation, including airplanes
  • shopping malls
  • furniture or second hand stores
  • urban areas
  • rented homes

Items commonly responsible for spreading bed bugs include:

  • used or secondhand furniture
  • new furniture or textiles exposed to bed bugs during transit
  • items of luggage
  • chairs or loungers where people fall asleep
  • bedding or bed clothes
  • moving or storage boxes
  • shipped items, especially if held at several locations or warehouses

Bed bugs do not have a preference between sanitary, messy, or unsanitary conditions.

They can, however, be found at higher rates in places, such as hotels, if infestations are not properly cleared.

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