Doctors have revealed which sense people lose first when death is just hours away.

There is only limited evidence when addressing questions surrounding a dying person's feelings and their experiences during final moments.

This is because death is discussed from the viewpoint of how relatives, loved ones and healthcare workers observe a patient, rather than testimonies from those departing - for understandable reasons.

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They are frequently too unwell or lethargic or unresponsive to provide an account.

It all remains rather cloaked in mystery.

Moreover, until around 100n years ago, death was swift - with contemporary medicine enabling patients to die gradually from prolonged illnesses.

For most people who pass away in this was, there's a sudden sharp decline during the final few days of life - termed "active dying".

James Hallenbeck, a palliative-care expert at Stanford University, explained people typically lose their senses and appetites in a particular sequence.

In Palliative Care Perspectives, his handbook on palliative care for doctors, he said: "First hunger and then thirst are lost. Speech is lost next, followed by vision.

"The last senses to go are usually hearing and touch."

There is also a widespread belief that people see a brilliant light as they pass.

David Hovda, the director of the UCLA Brain Injury Research Centre, explained the brain "starts to sacrifice areas which are less critical to survival", reports The Atlantic.

"As the brain begins to change and start to die, different parts become excited, and one of the parts that becomes excited is the visual system - and so that's where people begin to see light," he said.

This heightening of certain senses seems to back up what researchers understand about the brain's reaction to death.

Jimo Borjigin, a neuroscientist at the University of Michigan, observed that moments before animals die, brain chemicals suddenly spike.

Researchers were already aware that brain neurons keep firing after death, but this was distinct - the neurons were producing fresh chemicals in vast quantities.

Borjigin explained that cardiac arrest survivors report an "amazing experience in their brain" where they witness lights and everything feels "realer than real", which she attributes to this chemical release.

During the final hours, patients will have ceased eating and drinking, and lost their sight, before shutting their eyes and seeming to slumber.

Hallenbeck explained: "From this point on ... we can only infer what is actually happening.

"My impression is that this is not a coma, a state of unconsciousness, as many families and clinicians think, but something like a dream state."

The precise moment it occurs is difficult to determine.

"It's like a storm coming in," he added.

"The waves started coming up. But you can never say, well, when did the waves start coming up? ...The waves get higher and higher, and eventually, they carry the person out to sea."