Bed bugs find you through a combination of carbon dioxide in your breath, body heat, and chemical compounds your skin releases. These cues work at different distances, creating a trail that guides the bugs from across the room to your exposed skin. No single factor does the job alone. Instead, bed bugs rely on a layered detection system that kicks in as they get closer to a sleeping host.
Carbon Dioxide: The Long-Range Signal
The most powerful long-range attractant is the carbon dioxide you exhale. Bed bugs can detect elevated CO2 concentrations from several yards away, and this signal is what initially gets them moving out of their hiding spots. A study from the University of Sheffield found that when researchers raised CO2 levels in a room, bed bugs were significantly more likely to leave their refuge and begin actively searching for a host. This is one reason bed bugs tend to bite around the head, neck, and upper body: they’re following the CO2 plume back to its source.
Body Heat Works Only Up Close
Your body temperature matters, but only once a bed bug is already nearby. Research published in the Journal of Experimental Biology found that bed bugs could only detect heat from less than 3 centimeters away (about an inch). In controlled tests, bugs showed a clear preference for a surface heated to 38°C (just above normal skin temperature) when it was within 10 millimeters, but showed no preference at 30 or 50 millimeters. So heat isn’t what draws them across the room. It’s the final guidance system that helps them zero in on exposed skin once they’ve already arrived at the bed.
Temperature also influences feeding behavior. Bed bugs fed most readily on artificial blood sources heated between 38°C and 43°C, which mirrors the range of human skin and slightly above. At 48°C, feeding dropped off sharply.
Skin Odors That Bed Bugs Can Smell
Your skin constantly releases volatile compounds, and bed bugs have specialized sensory organs tuned to detect several of them. Researchers analyzing whole-body human odor found that bed bugs responded most strongly to a handful of chemicals naturally present on skin, particularly aldehydes (compounds produced by skin oils breaking down) and sulcatone, a substance found in human sweat and breath. These chemicals triggered responses in the bugs’ antennae even at very low concentrations, diluted 100,000 times from the original extract.
This sensitivity to skin odor explains a practical finding that travelers should know about: bed bugs are twice as likely to gather on dirty laundry as on clean laundry. A University of Sheffield study showed that in the absence of a human host, soiled clothes acted as a stand-in, attracting bugs through residual body odor. Leaving worn clothing in an open suitcase or on the floor of a hotel room can draw bed bugs straight to your belongings, which is one of the main ways they hitchhike to new locations.
Color Preferences
Bed bugs do show color preferences when choosing hiding spots. In lab tests published in the Journal of Medical Entomology, bugs consistently chose red and black shelters over other options, while avoiding yellow and green. Researchers believe the attraction to red may be because bed bugs themselves appear reddish-brown, and they’re drawn to aggregate with other bugs. The avoidance of lighter colors like yellow and green may be because those colors resemble brightly lit, exposed areas where bed bugs feel vulnerable.
That said, buying yellow sheets won’t protect you. Color preference affects where bugs hide, not whether they’ll feed on you. A hungry bed bug will cross any color of bedding to reach a warm, breathing human.
Why They Bite at Night
Bed bugs are nocturnal and prefer to feed in darkness, which aligns with when most people are asleep and still. They’re sensitive to light and tend to retreat from well-lit areas during the day. But this is a preference, not a rule. Leaving the lights on while you sleep will not stop bed bugs from feeding. When hungry enough, they’ll approach and bite regardless of lighting conditions. Their drive to feed overrides their preference for darkness.
In heavily infested rooms kept at typical indoor temperatures (around 26°C), female bed bugs feed roughly every 2.5 days. That frequent feeding cycle means the cues you produce, your breath, your warmth, your skin chemistry, are being sought out multiple times per week by every bug in the room.
Do Bed Bugs Prefer Certain People?
Some people seem to get bitten more than others, and there are a few possible explanations. Limited lab research has suggested bed bugs may feed slightly more often on people with type O blood compared to types A or B. But in real-world settings, proximity and accessibility matter far more than blood type. The person sleeping closest to the infestation gets bitten the most, regardless of their blood.
Alcohol consumption doesn’t appear to make you more attractive to bed bugs. In fact, research presented at the National Conference on Urban Entomology found the opposite effect on the bugs themselves: bed bugs that fed on blood mixed with alcohol grew far less and laid fewer eggs. Bugs fed clean blood doubled their body mass and laid an average of 44 eggs, while those fed blood with the highest alcohol concentration grew only 12.5 percent and laid about a dozen eggs. This doesn’t mean drinking protects you from bites, but it does suggest alcohol in your blood isn’t drawing them in.
The more significant variable is simply how much CO2 and body odor you produce. Larger people exhale more carbon dioxide. People who run warm or sweat more release greater quantities of the skin compounds bed bugs detect. These differences can make one person in a household a more frequent target than another, even when both sleep in the same room.
How to Use This Knowledge
Understanding what attracts bed bugs points to a few practical habits. When traveling, keep worn clothing sealed in plastic bags rather than leaving it draped over furniture or piled in an open suitcase. The residual body odor on dirty laundry is a proven attractant. Luggage racks that keep bags off the floor and away from walls also reduce the chance that bugs will climb aboard.
At home, the attractants that matter most, your breath and body heat, aren’t things you can change. This is why prevention focuses on barriers (mattress encasements, interceptor traps under bed legs) rather than repellents. Bed bugs are not attracted to dirt, food crumbs, or clutter. A spotless home is just as vulnerable as a messy one if bugs are introduced. What clutter does is give them more places to hide, making infestations harder to detect and treat.