No matter how often we may joke about it in public, snoring is no laughing matter. If your – or your partner’s - snoring is actually sleep apnoea, it could be a matter of life and death. Lesley Dobson reports

Most of us rely on a good night’s sleep to recharge our batteries. But for around 3.5% of men and 1.5% of women, sleep apnoea, a condition we may have without realising it, could be making our beds a battleground.

Obstructive sleep apnoea (OSA), to give its full name, is a serious condition where the muscles of the throat relax during sleep and totally block the sleeper’s airways. An apnoea usually lasts for around 10 seconds, during which time the sleeper suffers from lack of oxygen.

Symptoms usually include loud snoring, laboured and noisy breathing and possibly snorting during apnoea. People with OSA may have no idea of what’s going on while they sleep. However, these repeated interruptions to their sleep can make them irritable, depressed, very sleepy and with headaches and poor concentration.

Sleep apnoea has been linked with a risk of stroke for men in the past. Now a landmark study from the USA has shown that the link is much stronger than previously thought. And the study has shown for the first time that there’s also a link between OSA and a higher stroke risk in women.

Researchers from the Sleep Heart Health Study carried out the research with over 5,400 participants aged 40 and older, in nine medical centres in the USA. None had suffered a stroke before the study started. The researchers followed their subjects for an average of nine years.

The results showed that even men with mild sleep apnoea are at risk of stroke. And as the OSA gets worse, so the risk of stroke rises. Men with moderate to severe sleep apnoea were nearly three times more likely to have a stroke than men without sleep apnoea or with only mild OSA. Women, on the other hand, only had a significantly increased risk of stroke if they had severe OSA.

One reason for this difference between men and women may be that men are more likely to develop OSA at a younger age. "Our findings provide compelling evidence that obstructive sleep apnoea is a risk factor for stroke, especially in men," says Susan Redline, professor of medicine, paediatrics and epidemiology and biostatistics at Case Western Reserve University in Cleveland and lead author of the paper. "Overall, the increased risk of stroke in men with sleep apnoea is comparable to adding 10 years to a man’s age. Importantly, we found that increased stroke risk in men occurs even with relatively mild levels of sleep apnoea."

"Research on the effects of sleep apnoea not only increases our understanding of how lapses of breathing during sleep affect our health and wellbeing, but it can also provide important insight into how cardiovascular problems such as stroke and high blood pressure develop," said Michael J Twery, director of the NIH National Center on Sleep Disorders Research, an office administered by the National Heart, Lung and Blood Institute.

"These new data confirm the previous findings of an association between obstructive sleep apnoea and stroke, raising the possibility that we may be able to prevent some strokes by effectively treating obstructive sleep apnoea," says Dr Andrew Cummin, Sleep Centre Director at Imperial College Healthcare Trust.

"Other health risks of particular concern include high blood pressure and irregular heart rhythms. Sleep apnoea sufferers have also been found to be seven times more likely to have a car accident and may even fall asleep behind the wheel.

"If you or your partner are prone to heavy snoring in the night and feel tired constantly, it is important to ask your GP to refer you to a sleep centre. If you are diagnosed, you may be provided CPAP therapy, recommended by NICE as the gold standard treatment for sleep apnoea. The device delivers pressurised air through a mask that is worn each night in order to keep the airways open."

There’s more news for women on the stroke front. Another study, reported in Stroke: Journal of the American Heart Association, has shown that regular walking can reduce your risk of stroke. Compared to women who didn’t do any walking, women who walked at a brisk pace – three miles an hour or faster – had a 37% lower risk of any type of stroke. Women who walked for two hours or more a week had a 30% lower risk of any type of stroke.

The study followed 39,315 female health professionals (average age 54) for 11.9 years. All were taking part in the Women’s Health Study. Every two or three years the women reported their physical activity for the past year. During that time 579 women had a stroke.

Not sure if you’re walking at a brisk pace? Jacob Sattelmeir from Harvard School of Public Health in Boston Massachusetts and lead author of the paper suggests possibly using a heart rate monitor, or for a rough estimate, the 'talk test'. "For a brisk pace you should be able to talk but not able to sing. If you cannot talk, slow down a bit. If you can sing, walk a bit faster."

"150,000 people in the UK will have a stroke every year and it is the UK's third biggest killer," says Andrea Lane of The Stroke Association. "There are several known risk factors for stroke such as high blood pressure, smoking and obesity; however research is continually being undertaken to investigate other potential contributing factors and causes.

"Studies in the past have suggested that there may be a link between sleep apnoea and stroke. The NHLBI's study is the largest to date and it provides evidence to support this link. The Stroke Association would welcome further research on this topic and investigate whether treating sleep apnoea could reduce a person's risk of stroke.

"Everyone can help reduce their risk of stroke by making simple lifestyle changes, such as having regular blood pressure checks, giving up smoking, reducing alcohol intake, improving their diet and getting plenty of exercise."