How do bedbugs know that a person is sleeping? - briefly
Bedbugs detect a resting host by sensing body heat, carbon‑dioxide emissions, and the reduced movement and vibrations that accompany sleep, triggering their feeding behavior.
How do bedbugs know that a person is sleeping? - in detail
Bedbugs locate a resting host primarily through a combination of chemical, thermal, and mechanical signals that become prominent when a person is immobile for an extended period.
Carbon dioxide (CO₂) emitted from exhalation rises in the immediate vicinity of a sleeping individual. Specialized chemoreceptors on the insect’s antennae detect concentration gradients as low as 0.01 % above ambient levels, directing movement toward the source.
Heat emanates from the body and blankets, creating a localized temperature increase of 1–3 °C above room temperature. Thermoreceptors in the basal segments of the antennae and the tarsi sense this gradient, allowing the bug to home in on the warmest spot, typically a mattress edge or pillow.
Vibrational cues change markedly when a person lies still. Bedbugs possess mechanosensory hairs that respond to low‑frequency vibrations (10–100 Hz) generated by breathing and heartbeat. The reduction of higher‑frequency movements associated with waking activity signals a stable target.
Chemical signatures from skin oils, sweat, and pheromones also contribute. Olfactory receptors bind to fatty acids and lactic acid present in perspiration, reinforcing the location identified by CO₂ and heat.
During the night, bedbugs exhibit a circadian pattern of heightened activity that aligns with typical human sleep periods. Internal clocks synchronize feeding attempts with the host’s reduced defensive responses, maximizing blood intake efficiency.
The feeding sequence proceeds as follows:
- Approach: Antennae sample CO₂ and heat; movement ceases when gradients converge.
- Orientation: Tactile hairs confirm proximity; the insect aligns its head toward the host’s skin.
- Insertion: The proboscis penetrates the epidermis; the bug releases anticoagulants and anesthetics to facilitate uninterrupted feeding.
- Retention: Mechanical anchoring of the mouthparts and the host’s immobility keep the bug attached for 5–10 minutes.
After engorgement, the insect retreats to a concealed harbor, where it digests the blood meal over several days before re‑entering the search cycle. The integration of CO₂ detection, thermal sensing, vibration assessment, and chemical profiling enables bedbugs to reliably identify a sleeping host and time their feeding accordingly.