There are things a doctor must learn to do at night that nobody teaches you in medical school. You must learn to make decisions at 3am with incomplete information and a brain that has been awake for nineteen hours. You should trust your instincts, but you shouldn’t trust them blindly. And you have to learn when to call for help, which is harder than it sounds.

The night shift at King’s ran from ten in the evening until eight the next morning. By midnight, the department could be dealing with anything: stroke patients, road traffic accidents, cardiac arrests. One particular Friday night in November, we received a thirty-eight-year-old man named Kofi who had collapsed at a party. His companion said he had been complaining of a severe migraine for two hours before losing consciousness.

I couldn’t ignore the possibility of a haemorrhagic stroke � a bleed in the brain. The brain is extraordinarily sensitive to pressure. A bleed in the wrong place can cause permanent neurological damage within minutes. We had to act fast. I ordered a CT scan of his head immediately. While we waited, I checked his blood pressure � it was dangerously high. I started medication to bring it down.

The scan came back. There was a small bleed in the cerebral cortex. Not catastrophic � but serious. Kofi needed to be transferred to the neurology ward immediately. I called the neurology registrar. She arrived in six minutes � which, at 2am, is fast. Later she told me that my decision to act immediately, and not to wait for a second reading, might have made a significant difference.

There was also, that same night, a seventeen-year-old girl with a suspected appendicitis. Severe pain in the lower right abdomen, fever, nausea. She was terrified. Her mother was more terrified. I had to be calm for both of them. The surgeon on call would operate within the hour. She would be fine. I told them both this, and I meant it, and it was true.

By six in the morning, I had seen fourteen patients. I had drunk four cups of coffee and eaten half a biscuit that someone had left on the nurses’ station. The ward was quieter � that brief stillness before the day shift arrives and the noise begins again. I sat at the desk for a moment and I thought about Kofi and the girl and Edith and Terry and all the others. This is what people should understand about emergency medicine: it is not glamorous. It is careful, methodical, and relentless. And it is, without question, the only job I have ever wanted to do.