Low blood pressure made me faint when I got up in the night

WAKING suddenly from the deepest sleep, I couldn’t believe how cold and hard the mattress felt beneath me.

It was only as I tried to get up that the reality became clear: I wasn’t in bed, I was face down on a bathroom floor.

All I remember was getting out of bed to go to the bathroom and then, nothing.

I had a painful, egg-shaped lump on the left side of my forehead and a metallic taste in my mouth, from a bloodied lower lip — which suggested I’d passed out face first.

Alone in a London hotel room, having travelled to the capital for work — my husband, Martin, was at home with our daughter, Sophie, 200 miles away in Manchester — there were no witnesses to what had happened.

Thankfully I was able to see my GP the next day, who ran through possible causes.

It was only when the doctor cuffed my arm with a monitor that a likely explanation came to light: I had low blood pressure — a reading of 90/50 (normal is 120/80).

If the top number in a blood pressure reading goes below 100, as mine did, you are more likely to faint, explains Dr Jerome Ment, a consultant cardiologist at University Hospitals Birmingham NHS Trust.

‘Some people may be predisposed to low blood pressure and may not be aware of it until it reaches a critical level — triggered by, for example, dehydration — and it causes them to faint.’

Dehydration leads to a reduction in the amount of fluid in blood vessels and so pressure in blood vessels drops, adds Dr Glyn Thomas, a consultant cardiologist at the Bristol Heart Institute.

Suddenly standing from a sitting or sleeping position can also cause your blood pressure to drop, as it means the blood rushes to your legs, making you feel faint for a few seconds while the body adjusts.

Spooling back to the night of my faint, I realise that I’d been working late with nothing more than a salad and half a glass of tonic water since lunchtime and then I remember getting out of bed slowly.

‘If you’re deeply asleep, your heart rate and blood pressure are low, you’re in a nice, warm bed then suddenly get up, your body might not have time to acclimatise to the change,’ says Dr Thomas.

‘Gravity pulls the blood from the chest to the lower body and you don’t get enough blood to the brain, causing light-headedness and fainting.’

After tests ruled out other possible causes my only options were to make lifestyle changes such as taking care when getting out of bed and sleeping with the head slightly raised.

‘This encourages blood to pool in the lower body when you’re sleeping and tricks the body into thinking you are upright rather than lying down — so there is no sudden change in blood pressure when you stand up,’ says Dr Thomas.

‘Keep a glass of water by your bed and drink it when you wake up. Then wait for 20 minutes or so before getting up.’

Certainly I’m more cautious about not drinking enough fluid — I have no intention of sleeping anywhere other than a bed again.