She was just 19 when she suffered a stroke in her sleep one night.

Sharing her story ahead of the inaugural World Thrombosis Day on Monday, Mrs Cowie, now 28, said she had felt unwell, fatigued and had "some visual disturbances" in weeks before the stroke, but she did not know something was seriously wrong.

She saw a doctor and was booked off work on stress leave, but suffered her stroke the day she was due to return to work.

"I woke up and my alarm was going off but I wasn't really comprehending what was happening," she said.

"I felt like I had pins and needles down the left hand side of my body and when I went to get out of bed, I couldn't feel my left arm or leg.

"Being 19 and thinking you're a bit invincible, I just assumed I'd slept funny and I'd be fine."

Mrs Cowie said the left hand side of her face had dropped, but still she didn't suspect anything was seriously wrong.

When she attempted to leave for work, she couldn't drive because her leg "wasn't working".

She rang her mother who suggested she go to hospital. Canberra Hospital was nearest, and luckily had a stroke unit.

"They straight said they thought I was having a stroke," she said.

"It was pretty devastating."

She spent two weeks in the hospital's stroke unit and she had to undergo rehabilitation which lasted nearly two years.

It was not known what had caused her stroke.

"My blood pressure was fine, I was healthy, fit and active and not overweight," she said.

Despite the devastation of having a stroke at such a young age, Mrs Cowie said it gave her perspective and helped her realise what was important in life.

Since her stroke, she has become an ambassador for the National Stroke Foundation.

She encourages people to recognise the signs of stroke.

"Know the FAST test which stands for face, arm, speech and time. Every minute counts when you think someone is having a stroke," she said.

"Stroke doesn't discriminate and it can affect anybody at any time."

It is estimated blood clots kill more than 40 Australians a day, but new research released on Monday reveals nearly nine in 10 Australians are ignorant of the dangers of blood clots and don't see them as life-threatening.

Blood clots are responsible for the top three cardiovascular killers: heart attack, stroke and venous thromboembolism.

Associate Professor Andrew Lee, director of stroke clinical research at Flinders University, said thrombosis, or the formation of blood clots, was a major problem in Australia.

"It may account for up to 40-50 per cent of strokes in a condition called atrial fibrillation where there is an irregular heart beat and in clotting in general, it accounts for 85 per cent of strokes," he said.

Major risk factors for developing blood clots included an irregular heart beat, high blood pressure, diabetes, cholesterol, smoking as well as age.

"As people age, they really need to have their health checked out by their GP making sure they don't have any other risk factors," he said.