As a 30-year-old, Caroline Henaghan was busy. She was working for the UK’s Home Office while training to be a barrister, and wondered if the frequent stress and anxiety she was experiencing were just products of overwork and getting older. “It felt like getting on a hamster wheel and not being able to get off,” she recalls.

Eventually work got to be too much and she took an uncharacteristic short leave of absence. But Henaghan’s mood didn’t improve. She woke up each morning with enormous anxiety, leading to social withdrawal. “I would essentially do a disappearing act so I wouldn’t have to be around people,” she says. She was never suicidal, she stresses. But she did fantasise about leaving things behind. “It would be a case of if I could go to sleep and never wake up. That’s how dramatic it was for me.”

Though the psychiatric symptoms were the strongest, there were odd physical patterns as well. Henaghan would get bloated and fatigued, sleep excessively, and – as a keen gardener – shop erratically, for instance buying plants that were out of season. Her family noticed her increasingly strange behaviour as well. She thought it might be bipolar disorder, given the cyclical nature of her ups and downs. For instance, she might spend two weeks each month putting right the damage from the previous week: the fights with loved ones, the untidy home, the slippages at work. Eventually, after what she calls a “mini-breakdown”, she realised that the recurrence of all these symptoms was linked to her menstrual cycle.

Her doctors dismissed her concerns. She visited five GPs, all male, after the first one commented: “Oh, it’s just PMS. My wife gets that.”

But it wasn’t “just” premenstrual syndrome (PMS). Henaghan had to do what many women overlooked by the medical establishment do: her own research. Through her online study, she learned about a condition called premenstrual dysphoric disorder (PMDD).

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PMDD is much more intense than its better-known relative, PMS, with physical symptoms including fatigue and migraines, while the psychological symptoms can include the severe mood swings and anxiety that plagued Henaghan. The disorder can be so debilitating that 15% of those with PMDD have attempted suicide, and some young women affected are opting for hysterectomies.