Obstructive Sleep Apnoea Hypopnoea Syndrome(OSAHS)affects at least 4% of males and 2% of females.

OSAHS is the combination of excessive daytime sleepiness, snoring and apnoeas (stopping breathing at night). As well as affecting tiredness, mood, concentration and quality of life - there is growing concern that it can increase the risk of high blood pressure, heart problems, strokes and thromboses (clots in the veins).

It appears that OSAHS may affect the thickness of the blood and cause it to clot more easily it also causes damage to the lining of the blood vessels (endothelial injury). These effects seem independent of other risk factors such as obesity, smoking, family history of clots etc.

The investigators are testing new biomarkers: gel point and fractal dimension developed at the Swansea University to measure the 'clotting' of the blood in people with OSAHS and a similar group of people who snore and who are sleepy but do not have OSAHS on sleep studies (Controls) Also markers of vascular inflammation are being measured.

Primary objective:

The primary outcome of this study is to test the null hypothesis that no significant difference exists between fractal dimension (Df)and vascular injury markers including serum amyloid A (SAA), C-reactive protein (CRP), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1)in patients with OSAHS and sleepy, snoring controls of similar age, gender and BMI.

Secondary objectives:

1. To test the null hypothesis that there is no significant difference in measured markers before and after a night's sleep in OSAHS and controls.
2. To test the null hypothesis that there is no significant difference in measured markers following 1 month of CPAP treatment, in those with OSAHS.

Inclusion Criteria:

• 18-80 year old with h/o daytime sleepiness, snoring and apnoeas

Exclusion Criteria:

• Refusal to give written informed consent.
• Personal or family history of pro- thrombotic or bleeding disorders, severe liver disease (clotting problems) and those prescribed warfarin or heparin.
• Those with borderline sleep studies (4% Diprate or AHI 10-14 per hour).
• Aged less than 18 years or greater than 80 years.

Subjects are recruited prospectively from a specialist sleep-disordered breathing clinic in Prince Philip Hospital, Hywel Dda Health Board. They are referred from both primary and secondary care with varying degrees of symptoms suggestive of OSAHS (daytime sleepiness, snoring and/or nocturnal apneas).