It’s very distressing for a person with no known illness to go to bed only for them not to wake up the next morning. But what does it mean to die in your sleep; how does it happen in the first place?

Medical professionals point out that there is a health and scientific explanation for this.

Apparently, the brain remains active even as one sleeps. Research done by scientists from University of California holds that a cumulative loss of cells in the area of the brain that controls breathing can be a cause.

This condition is termed as central sleep apnoea. It is a disorder in which one’s breathing repeatedly stops and starts during sleep and it occurs because the brain doesn’t send proper signals to the muscles that control one’s breathing. This condition can lead to sudden cardiac death.

Another possible cause is Sudden Death Syndrome (SDS).

Dr Kenneth Ruzindana explains that some cases of this rare condition are mostly due to Sudden Death Syndrome, which is a loosely defined umbrella term for a series of cardiac syndromes that cause sudden cardiac arrest and possibly death.

He says that some of these syndromes are the result of structural problems in the heart.

"Others may be the result of irregularities within the electrical channels of the heart. All may cause unexpected and abrupt cardiac arrest, even in people who are otherwise healthy. Some people die as a result of it,” he says.

Dr Ruzindana notes that most people don’t know they have the syndrome until a cardiac arrest occurs.

"Many cases of SDS aren’t properly diagnosed, either. When a person with SDS dies, the death may be listed as a natural cause or heart attack. But if a post-mortem is performed to understand the precise cause, they may be able to detect signs of one of the syndromes of SDS,” the medic adds.

Dr Wilbur Bushara explains that high concentrations of carbon monoxide have potential to kill in a few minutes.

Household appliances, such as gas fires and central heating systems, are possible sources of carbon monoxide.

Dr Bushara says that though this gas has neither smell nor sound, it is very deadly explaining that this happens because it deprives the blood of oxygen.

"If this gas builds up in a room, for example, breathing it in can become toxic. When one inhales lots of it and it piles up in one’s lungs, it can be very deadly, especially if one is asleep. But if they are awake, they can at least experience symptoms, such as wooziness, body weakness and a slight headache, among others,” he says.

The case with ‘dry drowning’

An article on the Healthline website explains that when a child or adult falls in water, it’s human nature to inhale or gulp down water in a state of panic. Once the person has been rescued from the water, most would assume that the danger is over.

Some have labelled this condition ‘dry drowning’ though this is not a medical term or diagnosis. Doctors call this phenomenon "post-immersion syndrome,” and though it’s rare, it does happen.

The article indicates that this condition can occur when inhaled water, even just a drop or two, makes it past the throat and into the lungs. This usually causes symptoms such as coughing, chest pain and low energy or sleepiness after a water incident; however, these signs are sometimes mild and easy to miss.

Dr Bushara supplements this by noting that inhaled water can cause breathing problems that can get worse over time.

He notes that these problems can only surface hours or even days later after the incident, especially when the victim has fallen asleep.

He also highlights that some of the other factors that can trigger death while sleeping include; cerebral aneurysm — an abnormal focal dilation of an artery in the brain that results from a weakening of the inner muscular layer of a blood vessel wall.

The vessel develops a "blister-like” dilation that can become thin and rupture without warning, and this kind of haemorrhage can lead to a stroke or even death.

There is also the widowmaker heart attack. Medics explain that this type of heart attack happens when the left main artery gets blocked. Whereas other forms of heart attacks can jolt victims to their conscience before death occurs, this particular one doesn’t.

Is prevention possible?

Dr Bushara says it is important for one to look out for preventive measures, adding that this is only possible if one knows what to look out for.

"What this means, is that people should go for check-ups to look out for possible illnesses, this can certainly help in staying away from imminent and untimely death,” he says.

Some of these conditions, such as sleep apnoea, respiratory and heart problems are treatable, he adds.