Blame it on your hormones

A problem with any of your glands will result in a hormone imbalance that can present itself as a wide range of physical symptoms - including weight gain, thinning hair, acne and fatigue - but also a radical change in your moods.

Victoria Health's co-founder and pharmacist Shabir Daya explains that the endocrine glands, which produce all your hormones, are inter-linked in one system. "The ovaries communicate with your adrenals, which in turn communicate with your thyroid gland, and so on," she says. Which is why when there's a problem with one of your glands, all the others are affected too.

The reason hormones have such a profound effect on your moods, as well as your health, is that the parts of the brain involved in thinking, planning and emotions all possess receptors for oestrogen and progesterone.

Shabir Daya explains, "Most women are unaware that the decline in female hormones from your mid-thirties onwards puts a big strain on your adrenal glands - the body's workhorses when it comes to dealing with stress. The adrenals produce important hormones, such as cortisol - an energy releaser - and pregenolone, which brings about feelings of wellbeing. So, as you age, hormone levels drop and the resulting weak adrenal function can lead to depression, fatigue and insomnia."

Anti-ageing expert Dr Cecilia Tregear, from the Wimpole Skin Care Centre, agrees. "Hormones very much affect how you act and feel. If they're out of kilter, your behaviour will be affected. Naomi Campbell and Heather Mills both exhibit classic signs of hormonal imbalance, as they don't appear to cope well with stress," she says.