Do Bed Bugs Only Come Out at Night? Myths vs Facts

There’s a lot of misinformation about bed bugs online and in common knowledge. Believing the wrong things about bed bugs can lead people to underestimate an infestation, use ineffective treatments, or miss the signs entirely. Here we address the most persistent bed bug myths — starting with the big one.

Partly true — but misleading. Bed bugs are naturally nocturnal and prefer to feed when their host is asleep and still. However, they are not exclusively nocturnal. If they are hungry enough — or if the room is kept dark — they will feed during the day. People who work night shifts and sleep during the day are just as likely to be bitten.

A large, hungry infestation will not wait for darkness. As an infestation grows, bugs become more active and less cautious about when they feed.

False. Adult bed bugs are visible to the naked eye. They’re approximately 4–5mm long — roughly the size and shape of an apple seed — and reddish-brown in colour. After feeding, they become darker and more swollen. Nymphs (young bed bugs) are smaller and paler, which makes them harder to spot, but adult bugs are clearly visible with good lighting.

False. This is one of the most damaging myths because it causes people to dismiss the possibility of bed bugs in their own home. Bed bugs are not attracted to dirt or grime — they’re attracted to the carbon dioxide and body heat of their host. They’re just as likely to be found in a spotless five-star hotel room as in a neglected property. Cleanliness does not protect you from bed bugs.

False. Research suggests that around 30% of people show little or no skin reaction to bed bug bites. This means a significant proportion of people with bed bug infestations have no visible bites at all. By the time a co-habitant or partner starts reacting, the infestation may already be well-established.

False. Bed bugs have no wings and cannot jump. They can only crawl. They are, however, surprisingly quick crawlers and can travel several metres in a short time. They spread primarily by hitching rides on luggage, clothing, and furniture — not by jumping between people.

False. Bed bugs spend the vast majority of their time in harbouring sites away from your mattress — behind headboards, inside bedside furniture, along skirting boards, within wall voids, and inside electrical outlets. Your mattress might appear clean while a significant infestation exists nearby.

False — unless your heating can reach 50°C+ throughout every item in the room. Standard domestic central heating reaches around 20–22°C, which has no effect on bed bugs. Professional heat treatment reaches 50–60°C and maintains that temperature for hours. Home heating is nowhere near sufficient.

False. While mattresses are a common harbouring site, bed bugs can be found throughout a property. Common locations include headboards, bed frames, sofas, carpets, skirting boards, picture frames, electrical outlets, behind peeling wallpaper, inside walls, and in curtains and soft furnishings. A thorough professional treatment needs to address the whole environment, not just the mattress.

Almost certainly false. Many UK bed bug populations have developed significant resistance to the pyrethroid insecticides found in shop-bought sprays. Even where resistance isn’t a factor, sprays only kill bugs they contact directly and cannot reach eggs hidden in seams, crevices, and walls. Over-the-counter products are rarely effective against established infestations.

Professional heat treatment is the most effective method for eliminating bed bugs. It kills bugs at every life stage — including eggs — in a single treatment session, regardless of insecticide resistance. It works throughout the environment, not just on surfaces.

If you have bed bugs, the most effective thing you can do is call a professional as quickly as possible. The sooner an infestation is treated, the smaller it will be and the easier it is to eradicate.