Yasmin Alibhai-Brown: When my time comes, I want to be allowed help to die

Ten days ago I fell when rushing into a tube station and injured my knee. It's been slow walking and climbing, a lot of stumbling, and only showers since then. At the weekend I thought I would try a long, deep bath. Tried to get up, then slipped, and had to call Mr Brown, who pulled me up. I hated it, hated it, the helplessness and dependence, even though the man is kind, and will, he says, take care of me if I am ever seriously disabled or infirm. His sweet promises only make me nervy and panicky.

Life, I have always thought, is good when one still has the capacity for some autonomy and pleasure. Individuals have their own definitions of both, and many do want to wait until the final flicker before the wick is burnt out. Better here than where macabre death takes you, they must think. Or perhaps they trust in God's will. Perhaps some can still feel real joy even when incapacitated by old age.

Not me, for sure. I will be miserable and inconsolable and cranky, and demanding and shouty, and will become a drain on my family. If I love them I should set them free of me when I am a burden – suffering, say, from terminal illness or serious geriatric disabilities. Why should I consume so much of their short time on earth, have them share my most wretched days?

Seems the stupendously talented actor Patrick Stewart is also determined that he will beam himself up when he's ready. People of sound mind should be allowed to decide when to exit an intolerable life, he believes.

Last week, Angela Scoular, wife of the actor Leslie Phillips and once a beautiful Bond girl, apparently killed herself. Only 65, she was suffering from bowel cancer. There have been many other such cases. Dignity in Dying, of which Stewart is a patron, is gaining public support – 66 per cent in a poll believe assisted suicides should be lawful. This week we were also reminded of Lynn Gilderdale, who became ill with ME when only 14 and was bedridden and in agony for 16 years before deciding she couldn't carry on.

On her blog she wrote: "I have had enough of this miserable excuse of a life ... I want to die. I really, really, really want to die." In December 2008 Lynn injected herself with a high dose of morphine but it didn't kill her. Her own mother, Kay, a nurse, then gave her more, as well as powdered sleeping pills, to help end it all. She was acquitted of murder and has now written a book, One Last Goodbye, and spoken on BBC Radio 4's Woman's Hour. Anyone who heard this mother would have both wept and truly understood why sometimes letting go is the only humane thing to do.

The debate about elective deaths in this country is still too polarised, too predictable and too ill-considered – pre-modern almost, and self-limited. It takes no account of the vast societal, environmental and scientific transformations of the past 50 years and the expectations of individuals. Once reproduction becomes a choice, death cannot then be left to the will of others or the law.

The case is well made for allowing the terminally ill to die before they go through total degeneration and we have had well-publicised cases where the courts and public get that "right". Most people won't step into the thornier terrain of extended life expectancy – the grey population now around longer than ever before.

You see some of them in nursing homes – inert, staring into the void (what are they looking at with those cloudy, dreamy eyes?), cared for by kind or unkind strangers, waiting for the bus of death to come and take them away. Just because doctors can keep them ticking over, doesn't mean they should. They are being kind to be inadvertently cruel in my view.

There are plenty of people who aren't in that pitiful space between real life and actual death. In the 18th century most people died in their forties in this country, toothless and often in great pain. Now, the middle classes upwards live longer and better – great stuff. Mortality, however, is unvanquished. We are transients. That's how it must be. Not necessarily, say a growing band of "seniors", as they like to be called.

Catherine Mayer, London bureau chief of Time magazine, has a book just out titled Amortality, The Pleasures and Perils of Living Agelessly. "Amortals [a term coined by Mayer for people who refuse to grow old] don't just dread extinction, they deny it." They will not quietly go beige or even age.

Mayer quotes Cambridge University gerontologist Aubrey de Grey ( yes, really!) who is confident that scientists "are in serious striking distance of stopping ageing ... it is possible to extend human life indefinitely". Hang on. Surely there must come an end to oldie fun and games, time to flush away the Viagra and dump the muscle tightening trainers. We must step aside, pass on. Imagine the population size if we refuse to bow out. The earth itself would perish. We can't be that greedy.

Campaigners against euthanasia believe passionately in the sanctity of life. So do I. But not a living death. They say individuals could be pushed to commit suicide by impatient or covetous relatives. So far there is no evidence of such wickedness on any scale in places like Oregon or the Netherlands, where assisted or self-determined suicide is legal and the state ensures no foul play. There is understandable concern that in Holland palliative care is now not what it should be, and that could be because of legalised suicide. That said, on balance, it is wrong and unjust to insist that the very old and very ill must hang in there even when they want to sleep in eternal peace.

The author Terry Pratchett, who has Alzheimer's disease, spoke for many when he said in his Dimbleby Lecture last year: "If I knew I could die, I would live my life. My life, my death, my choice." That is how I feel, and I hope that my beloved husband and children will let go when the time comes. And plant a jasmine bush to waft its scent through the garden, and whisper that I am fine wherever I am.

y.alibhaibrown@independent.co.uk