Crown Princess Mette-Marit has been suffering from vertigo.
Crown Princess Mette-Marit and Crown Prince Haakon
The 44-year-old Crown Princess of Norway has been forced to pull out of several royal engagements in recent months after she was left bedridden by the illness which is commonly caused by a problem with the way balance works inside the inner ear, and is categorised by a sensation of dizziness which can last anywhere from a few seconds to over an hour.
Mette-Marit admitted she was struck by the sensation that she'd "overindulged" on a ferryboat in November when she cancelled a royal visit to Denmark, and believed it to be the menopause at first.
Speaking to Norwegian radio station P3, she said: "I turned my head quickly, and it was like the whole world began to move. I began to sweat and felt nauseous - I thought I'd started early menopause."
The Crown Princess - who has Princess Ingrid, 13, and Prince Sverre, 12, with her husband Crown Prince Haakon, as well as 20-year-old son Marius from her previous relationship with Morten Borg - was undergoing a rigorous week of exercise when the condition struck her.
She added: "I'd been incredibly good at training this fall. We used a program that changed from week to week."
Vertigo usually goes away on its own, but it can come back at any time, and Mette-Marit will no doubt be keeping her eye on her condition in the future.
Her comments come after Norway's royal palace said the Crown Princess was suffering from Benign Paroxysmal Positional Vertigo (BPPV), which can cause a loss of balance, dizziness and nausea.