Drinking coffee, having sex and even blowing your nose can be enough to trigger a potentially fatal brain haemorrhage, research has shown.
All feature in a list of trigger factors that boost the chances of a weakened blood vessel, or aneurysm, bursting in the brain.
Coffee consumption was at the top of the table and increased the risk by 10.6 per cent.
Next came vigorous physical exercise (7.9 per cent) followed by nose blowing (5.4 per cent) and sexual intercourse (4.3 per cent).
Other risk factors were straining on the toilet, cola consumption, being startled, and getting angry.
“All of the triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture,” said lead researcher Monique Vlak, from the University Medical Centre in Utrecht, The Netherlands.
The study, published in the American Heart Association journal Stroke, looked at 250 haemorrhagic stroke patients who answered questions about their exposure to 30 potential trigger factors.
Relative risks were then calculated on the basis of brain bleeds being triggered by pre-ceding events.
Aneurysms in the brain cause the walls of blood vessels to balloon, leading to a risk of rupture and the sudden release of blood. This type of stroke known as a “subarachnoid haemorrhage” can have fatal or disabling effects.
An estimated two per cent of the population have intracranial aneurysms but few of them rupture.
When they do, it often occurs without warning. Sometimes a rupture is preceded by symptoms such as vomiting, impaired vision, fainting and severe headaches.
Dr Vlak said: “Reducing caffeine consumption or treating constipated patients with unruptured IAs with laxatives may lower the risk of subarachnoid haemorrhage.
“Whether prescribing antihypertensive (blood pressure lowering) drugs to patients with unruptured IAs is beneficial in terms of preventing aneurysmal rupture still needs to be further investigated.”
Sharlin Ahmed, from the Stroke Association, said: “The rupture of a brain aneurysm is incredibly dangerous. It is often sudden, without warning and it can cause bleeding in the brain, known as a haemorrhagic stroke.
“A sudden surge in high blood pressure can increase the likelihood of an aneurysm rupturing. However, it’s very difficult to determine whether the triggers identified in this study are definitely related to the onset of a stroke as they could simply be put down to coincidence.
“A lot more research needs to be carried out to assess whether each of the identified triggers could directly cause an aneurysm to rupture.”