Bed bugs are small, parasitic insects that feed exclusively on blood. They are a nuisance pest that can be very difficult to get rid of once established in a home. Many people wonder if bed bugs can actually sense when a person is asleep before coming out to feed.
Do bed bugs only come out at night?
It is true that bed bugs are most active at night when people are sleeping. However, they are not completely nocturnal and will venture out during the daytime if hungry enough. But nighttime is still prime feeding time for bed bugs for a couple of reasons:
- The darkness helps conceal them from detection as they crawl out to bite.
- Sleeping humans are stationary targets who don’t notice the stealthy pests until they wake up with bites.
So while bed bugs don’t necessarily “know” a person is asleep, their behavior patterns align with human sleep cycles, making night an ideal time for them to feed undisturbed.
How do bed bugs locate hosts?
Bed bugs don’t have eyes that can actually see in detail. So how do they know where to find a sleeping human to bite? Here are the main sensory cues that draw bed bugs toward their next meal:
- Body heat – Bed bugs are attracted to the warmth given off by a human body, especially at night when hosts are tucked into bed.
- Carbon dioxide – The CO2 gas humans exhale is another signal that helps guide bed bugs toward their target.
- Scent – The bugs can detect certain chemicals and compounds from human skin and sweat.
From the bed bug’s perspective, a sleeping human emits strong sensory signals – more heat, more CO2, stronger odors – that scream “host here, come feed!” Their instincts drive them to follow these cues to find a blood meal.
Do bed bugs intentionally wait for sleep?
It may seem like bed bugs “know” when you’re asleep and purposefully wait until then to bite. But the reality is that they likely don’t possess enough intelligence to discern sleeping humans from awake ones.
Instead, bed bugs usually just hide out nearby and wait for periodic opportunities to feed. When those strong host signals – heat, CO2, scent – become available at night, that triggers the bed bugs to venture out in search of blood.
So rather than intentionally biding their time, bed bugs are simply programmed to follow feeding prompts that naturally coincide with human slumber. Their actions give the appearance that they “know” you’re asleep, but it’s not an actual cognitive decision.
How quickly do bed bugs feed?
Once a bed bug locates a sleeping host, how long does it take to bite and feed? Adult bed bugs typically take 3-10 minutes to engorge with blood. Nymphs may take a bit longer, around 15-20 minutes. Newly hatched bed bugs are even smaller and will feed for 30 minutes or more.
Here are some key factors about bed bug feeding:
- They inject an anticoagulant when they bite so blood keeps flowing.
- Most feed for about 5-10 minutes before getting full.
- Engorged bed bugs swell up and become elongated and red.
- They can survive months between feedings if necessary.
The quick and furtive nature of their biting enables most people to remain undisturbed as bed bugs drink their fill of blood at night.
Do bed bugs take multiple bites?
In addition to feeding rapidly, bed bugs also tend to bite multiple times during a feeding session. They rarely get a full meal from one single bite. There are a couple reasons for this:
- Their small size limits how much blood can be ingested at once.
- Humans react by shifting position, forcing them to relocate and bite again.
- Different spots may provide easier access to capillaries for feeding.
As evidence of their multiple biting behavior, people often awake to find grouped clusters of 3-4 bites in a line or “breakfast, lunch, and dinner” pattern.
What time of night are bed bugs most active?
Bed bug activity reaches its peak in the middle of the night when most humans are in deep sleep. The exact hours of heightened feeding activity depend on when people go to sleep and wake up.
But generally, peak activity occurs in the early morning hours sometime between midnight and 5 AM. During these dark, quiet pre-dawn times, sleeping hosts emit the strongest sensory cues that summon bed bugs to bite. Activity tapers off as sunrise approaches and most people wake up.
Can bed bugs bite during the day?
While bed bugs prefer feeding at night, they can and will bite during daylight hours if given the opportunity. Common daytime biting scenarios include:
- Someone sleeping or napping during the day in an infested area.
- Sitting still in an infested room for an extended time.
- Cluttered rooms with lots of hiding spots nearby.
If a bed bug gets extremely hungry and senses a nearby host, some occasional daytime biting does occur. But the majority of feeding activity still happens during normal human sleep cycles at night.
Do bed bugs only feed on humans?
Humans are the preferred host of bed bugs, but they are also known to feed on other warm-blooded animals if necessary. Common alternative blood meal sources include:
- Bats
- Rodents
- Birds
- Pets – cats, dogs
These animals can also transport bed bugs into human living spaces. But they don’t make ideal permanent hosts compared to humans who provide regular, abundant meals for bed bugs.
How often do bed bugs need to feed?
Typically, adult bed bugs need to feed about once every 7-10 days to sustain themselves. Nymphs may be able to survive slightly longer, around 2 weeks between meals. But they will begin to die after a month or so without feeding.
Newly hatched bed bugs are tiny and don’t need huge blood meals. They may survive up to 2-3 months without feeding after emerging from eggs. But a blood meal is required for them to progress through growth stages and become reproductive adults.
Do bed bugs feed until they burst?
Interestingly, bed bugs have the ability to ingest over 6 times their body weight in blood. However, they do not feed to the point of bursting. Instead, their bodies expand and elongate to accommodate large blood meals.
When fully engorged, bed bugs become temporarily immobilized and must spend time digesting their meal. Their body has to expand gradually to handle excess blood intake. Sudden over-engorgement can result in internal rupturing and death.
How much blood can a bed bug consume?
An average adult bed bug drinks approximately 3-7 microliters of blood in one feeding. To put this in perspective:
- 1 microliter (μl) = one millionth of a liter
- An adult bed bug weighs about 5 milligrams
- It consumes over 10 times its weight in blood per feeding
Bed bug nymphs consume much less blood than adults, closer to 1-3 microliters per meal. But relative to body size, their blood intake is still very substantial.
Conclusion
While bed bugs don’t intentionally wait until you’re asleep to bite, their biology and behavior definitely align with human sleep cycles. Peak feeding activity occurs in the middle of the night when sleeping humans emit strong sensory cues. But occasional daytime bites can still happen with extended proximity to a host. Understanding details of how bed bugs feed can help with control efforts to eradicate these stubborn pests.