My thoughts would be that the snakes enter homes at night because they are looking for a heat source. The warmest source in the house is likely to be the bed because of human body heat. The bite will no doubt occur due to the snake feeling threatened when the sleeping person moves on it or near it.

As for snakes entering homes and beds I can hypothesis that it because of one or more of the following reasons:

1) As the bites happen in rural areas I assume they are low income areas, where the bed is likely to be low to the ground (or on the ground) and likely the only heat source in the building. This would cause any snake in the building and looking for heat to head directly to the bed.

2) Rural areas are often cooler than urban areas due to increased levels of exposure and lower density of humans and human activity. What are the night time temperatures in the rural areas out of interest?

3) Snakes are very common in rural areas with farms and agriculture as they actively prey on pests such as mice and rats. It is likely that there are high numbers of snakes in the area as a result of this and they are probably well habituated to human presence. So they don't have as much fear of humans as normal/ see a house as a good food source.

Also it being a rural area there are less humans and human activities to disturb the snakes.

Snakes only bite in defense so I can guarantee that snakes are not entering houses to attack or eat people.

I hope this helps?

Dan

I agree with your observations, Daniel! The problem is that most of these snakes are kraits, who live near human dwellings and are active during night time.  Due to expansion of the population, the humans have built their houses within the fields, which were the natural habitat of these snakes for thousands of years.

In rural areas, people sleep on floors and are not even safe on beds, especially on the ground floors.

Krait bites are not very painful and many victims don't even recognize the bite during sleep.  They are mostly found paralyzed in the morning, sometimes even dead.

Number of such bites occurring in this region are in hundreds.  I was thinking of some simple low cost engineering method or some chemicals, repellents etc, which can keep these snakes away from the houses at least.

What do you say?

Yes, Kraits were what I was thinking of. I have a friend from Chennai who was bitten by one, he just escaped with his life.

Bites in the hundreds?? That is very worrying!

The best way to reduce snake numbers is to reduce their prey, this is of course very difficult to impossible in rural areas.

I also imagine it would be very difficult to "snake proof" every rural building as snakes are exceptionally good at climbing and fitting into small places. On a small scale I would suggest that, but this is not a small scale thing.

One suggestion I do have is selective planting of particular plants. Some plants (found in India) are believed to repel snakes. I have not seen any scientific basis but Cymbopogon citratus (West Indian Lemon Grass), Rauwolfia serpentina (Indian Snake Root) and Andrographis paniculata are said to keep snakes away. I think these could be viable and cheap options. With the added bonus of being natural and locally sourced.

Other ideas that may or may not help:

Raising beds off the ground with metal poles (metal tends to stay cool and has a unnatural feel to a snake, it may also prevent climbing if it is smooth enough.

Placing flour round the outer edges of the bedroom, that way if a snake comes in the entry point(s) can be found and blocked, hopefully preventing a repeat entry.

Thank you Daniel!

That was a really helpful post.

I am wondering however,  that the Rangoli (colourful line drawings using flour, turmeric and other colorful household substances), that the people in South India draw near the entrance of their houses, may be serving the same purpose as a flour line suggested by you.  And we all thought that Rangoli is a hobby or a religious thing. Strange!!

My pleasure Vivek!

I think Rangoli would work perfectly.

Glad to have been of use!

Vivek think about using snake nets as we have mosquito nets  . Nets which are impermeable to these reptiles is another scientifically proven option. I am not sure about  the cost of these nets. 

i hundred percent agree with Daniel James Nicholson and subsequent partipants's observation. when sleeping person changes his position, the snake is threatened and bites, mostly the snake involved are kraits....it is why they are known "pean" in Sindh Province, that the snake  sucks sleeping person's breath......pushing him in death. several  cases i know personally over the years. 

snake bite cases during sleep are equally common in big cities like Rawalpindi and Lahore and elsewhere in Pakistan.

In French Guiana, we never notice  bittings by snakes during a sleep.

Of course we don't have Krait "only" coral snakes and pit-vipers.

In tropical forest, people sleep in hammock, perhaps it is one of explanation of no sleeping bitting in this country.

Folks an interesting discussion. Also non-venomous snakes enter dwellings for a number of reasons, a heat source, food (mice rats etc). People are accidentally bitten when they move during their sleep period or possibly get hit when awakening to go to the bathroom

@ Christian. People sleeping in hammock. That does not happen in our country. Though that is a good way of avoiding snakes! But, I am not sure how well it goes with your back when you sleep in hammock every night. I do not have any personal experience.

Vivek. In Hammock we sleep not very well for the first night but more and more confortably with time. With the use of mosquito net we avoid snakes, mosquitos, vampire bats. We use to controle hammock every time before to lay down; any scolopendra or spider can wait inside for you.

Scorpions and spiders are  responsible for most of night indoor envenomisations

I did not mention spiders/scorpions because of the subject title about snake bites. Yes I agree many other organisms have a potential for a sting/bite

There are a handful of reasons snake bites occur at night in rural homes and I cited them below:

Snakes inhabit tropical areas, such as homes in rural areas of Latin America that are often in poor condition with garbage or litter accumulating outside, where there are always small rodents. These places become the perfect habitat for snakes as they find shelter and food, facilitating their entry into these homes and, in turn, these kinds of accidents.

Snakes do not attack unprovoked. Bites often occur when someone steps on a snake by accident because of poor visibility or when someone rolls over onto a snake in bed. Studies in Latin America show that most accidents happen in the early morning, when there is more movement.

Perhaps most important, snakes are nocturnal, hence the reason for nighttime bites.

A snake’s biology can cause bites as well because they hunt their prey by sensing body heat and vibrations, leading to human bites.

I hope, these would help you

yes, snakes do not bite for fun, they either bite in defense or hunt for food. naturally larger animals are either avoided or when sensing danger from them are bitten only in self defense.

the pray is always bitten to subdue for the purpose of eating it.

some time the snake does not bite to inflict death, it just bite to deter and save itself.

I live in a rural area (desert) with lots of snakes. Few venomous ones.  I have never had one enter the house, but often in the summer I find them in sheds on the property. I hear that snakes sometimes come in houses here through gray-water pipes that lead to the inside.  I second the opinion that snakes to do bite unless provoked. If a snake gets into a bed and someone rolls over on top of it, snake bite would likely follow.

Reptiles which includes snakes  have evolved venom for the purpose of immobilizing prey. Snakes definitely will bite when they are cornered, accidentally stepped upon and in the case of indoor accidents such as startling a snake when one is a sleep by rolling over on it, making some sudden movement etc. Yes snakes will enter a house, dwelling building when any opportunity allows it self. Open doors, windows with no or torn screens, pipes and electrical cords that run the wiring in a house

Sr. Vivek :  Tengo experiencia casos de mordeduras, por serpientes del género Bothrops, en pacientes durmiendo : una enfermera del hospital de Leticia Amazonas, mientras dormía, cerca de ella tenía un ventilador , pequeño, en la mesa de noche. La serpiente descansaba en  el ventilador, y la enfermera, al moverse entendió el brazo tocó el ofidio y éste la mordió en hombro.

Durante el invierno, en la época de lluvia en la región amazónica, en los meses de Diciembre a Mayo,  el río inunda las tierra bajas entonces las serpientes buscan refugio en las tierras altas donde los indígenas tienen las viviendas y en esta época tenemos la mayor incidencias de mordeduras.

Otro paciente fue mordido, en el muslo , cuando al irse acostar, la serpiente estaba en lecho.

Estos accidentes ocurren cuando el paciente se mueve y toca el ofidio. 

Atentamente.

J. Silva Haad.

In French Guiana, a 2 years old girl was bitten at 2 o'clock in afternoon by a young Bothrops atrox who enter in her bedroom. The bite was under her left eye (two punctures). We found the snake only a week after the bite; it was crawling in the kitchen (30 cm so less than a month old). The hypothesis is that the snake was inside the toy basket of the little girl and bit her when she was taking a toy to play with.

I agree that snakes (and all reptiles too) do not attack people. Snakes (all reptiles) can bite  when somebody touch them. Snakes do not attack unprovoked. In the centre of Europe, Vipera berus (adder) bites during the day - in wild. In tropical zone and in deserts (my experience from Marroco) people have to protect the houses. Night active snakes (majority of snakes are going to hunt on the evening hours) would visit stable of farm animals (high temperature, optimal humidity, perfect substrate for egg laying), or even the house. The problem is on the side of people, so we have to close the houses (doors, windows ..).

Why do snakes bite people sleeping in their homes in rural areas? - ResearchGate. Available from: https://www.researchgate.net/post/Why_do_snakes_bite_people_sleeping_in_their_homes_in_rural_areas [accessed Sep 11, 2015].

I have done a large study on snakebite in children over 2 years . we have seen lots of cases of snake bites in night. in my own study i found the incidence of snake bites in night is 36.4%.

causes

1. provocation is more common at night due to darkness and drowsiness of people

2. people sleeping on floor without mosquito net are unable to flee when snake is in vicinity 

3 poor people in tropical country sleep in muddy kaccha thatched houses. Krait is notorious for dwelling inside these houses 

Snakes do not control their body temperatures and if the temperature drops they tend to find a warm place to inhabit. Unfortunately the snake finds a mammalian like a human who is a sleep and is warm. When the person moves in bed at night it can startle a response from the snake who is there to benefit the warm area it has decided to inhabit.

Then when a person has moved which humans and other animals do when they are asleep the snake of course is startled and a bite response may happen. About neurotoxic bites occurring at a certain time period may be due to a particular snake that inhabits the area where the person has been bitten

because, the sleeper do not know there is a snake in the bed, as he changes sides,nor moves limb, threaten the snake, so it bites.