No you're not bonkers... it's the menopause!
In this extract from her guide to surviving the change - So... That's Why I'm Bonkers! - Sheila gives her insightful and often hilarious advice on how women can navigate their way through...
What is the menopause?
The menopause is the end of fertility, when our ovaries stop producing an egg every four weeks.
It may not make the most sophisticated dinner party conversation, but it's definitely the big topic of discussion among women of a certain age, usually while fanning themselves.
"Oh, another hot flush, must be my age," they say, dismissing the feeling they'd been set alight by a stray firework.
But then it gets more serious. After three months of no sleep, anxiety attacks and palpitations, women begin to worry that it's not the menopause - that they're actually dying.
Until recently there has been no need to define what the menopause is within the health service. But The National Institute for Health and Care Excellence (NICE) has now defined a range of guidelines which are available to the medical profession. Let's hope they take more notice of them than my GP.
In the UK, the average age for a woman to reach the menopause is 51, but some can experience it as early as their 30s or 40s.
In women under 50, the menopause is diagnosed after 24 months without a period.
Over 50, it's diagnosed after 12 months without a period. In women with a sense of humour, it's diagnosed over a few bottles of wine and the general consensus is that getting older sucks.
Menstruation can sometimes stop suddenly at this point in life which at first might seem like a blessing. However, it's more likely that your periods will become less frequent before they stop altogether.
And they will catch you out when you least expect it - probably when there's no access to sanitary products.
Myths of the menopause
It begins at 50
Well, it could be that your menopause begins at 50, but your friends might start at 40, 46 or 61. The average age is around 51, but it doesn't happen overnight - often it's a gradual onset of symptoms, if you get any at all.
Also, some women don't realise they could start having symptoms many months or years before the onset of menopause. The odd hot flush, unusual fatigue, mood swings, irritability and weight gain are all possible during this phase which is known as the perimeno-pause, while still getting periods.
You're officially old
The menopause doesn't mean getting old either. A woman can expect to live decades past menopause and she will spend a large portion of her life when it's all over and still feel healthy, energetic and motivated.
It's a disease
One of the biggest misconceptions is that it's a disease which requires rapid treatment.
The symptoms may be uncomfortable, and some may demand immediate respite, but the menopause is normal and natural.
You can't get pregnant
Pregnancy can occur if you are still experiencing menstrual cycles, however irregular. Although this does require sexual activity with a living male.
Symptoms of the change
At last count there were at least 35 different symptoms that have been, or can be, attributed to the menopause.
A part from the hot flushes, mood swings, vaginal dryness and murderous personalities, a friend spent years investigating what she thought was a serious heart complaint, until a specialist told her that all her palpitations and missed beats were undoubtedly down to a lack of oestrogen. And because the list of possible side-effects seems to be endless - from a sudden allergy to hair dye or a persistent wind problem - it's rare that women seek medical intervention unless the symptoms become unbearable. Although anyone living within shouting distance might feel they need a doctor too.
The more common symptoms include weight gain and mood swings, although it would be understandable that the mood swings come from the weight gain.
The hot flush, usually accompanied by sweating, is said to be the most common symptom. More than 80% of women suffer from the problem which arises as changes in hormone levels upset the temperatureregulating part of the brain.
Thankfully, the inability to hold a thought for no longer than a goldfish means that women will forget what is troubling them.
It's a known fact that there's a tendency to memory lapses during the menopause which can happen because of disturbed sleep, although it isn't permanent.
I managed to get round it by ditching my pride and giving in to post-it notes and lists.
And finally, there's now proof that the menopause can drive you mad. Psychiatrists say there is a connection between hormonal changes and psychiatric symptoms, and women in the perimenopausal period are more likely to experience panic attacks and other anxiety symptoms.
Out of the ordinary
For some people, the change is relatively straightforward - a few hot flushes and irregular periods, and then it's all over. Those we call the 'deeply blessed'.
But for others, the symptoms can be both extreme and unusual.
Around 1% of women will suffer from unexplained premature ovarian failure (POF), when the menopause starts before the age of 40 - and up to 6% will experience premature menopause.
And just when you thought one of the benefits of getting older would be no more spots, a temporary bout of acne can rear its ugly head.
Many women suffer from vaginal dryness, bladder problems and painful sex because of a lack of lubrication.
However, vaginal atrophy - which sounds a bit like our lower bits are crumbling like the cliffs of Dover - refers to more extreme symptoms, such as irritation, bleeding and discharge.
Feeling suddenly giddy or light-headed is also a sign of low oestrogen because the hormone affects our nervous system, circulation and temperature control.
Another lesser known symptom of the menopause is crawling skin. Rather than blame the cat for having fleas, the sensation of ants crawling over or under your skin is caused by skin receptors adapting to having less oestrogen.
Bending down to scratch the itchy bits can become a problem too. Creaking knees, aching backs and a lack of flexibility are all possible symptoms.
Menopausal women tend to get soreness at the base of the thumbs, the elbows, knees, back and neck. And if that isn't enough, hip pain can also be a problem.
Stretching exercises - such as yoga and pilates - can help, as can losing weight and building more muscle with weight training.
Losing your libido
Anyone who has seen Sex And The City might feel the world is on fire with raging lust, which is fine if all your 'bits' are in working order. For those who have contemplated joining a convent when the Big M kicks in, it can all seem very out of sync with reality.
Of course, it isn't just the fact that the desire is missing. Many women start to encounter pain instead of pleasure during sex - which rather removes the incentive to take part.
But if the tried and trusted lubricant methods aren't working, there are a number of natural products claiming to help women regain their sexual desire, including Sarsaparilla and Tribulus.
If you still think your partner is about as attractive as a warthog, then it might be worth trying couples counselling.
Adapted by Siobhan McNally from: So... That's Why I'm Bonkers! A Girl's Guide to Surviving The Menopause, by Sheila Wenborne, PS7.99, amazon.co.uk
"In women with a sense of humour the change is usually diagnosed over a few bottles of wine