Obstructive sleep apnoea syndrome is associated with increased morbidity and mortality. It is characterized by partial or complete collapse of the upper airways during sleep leading to impaired gas exchange and recurrent arousal from sleep. The consequences of OSAS include excessive daytime sleepiness, cognitive dysfunction, impaired work performance, and impairment in health-related quality of life. Observational and experimental evidence suggests that obstructive sleep apnea may contribute to the development of systemic hypertension, [4] cardiovasculardisease, [5] and abnormalities in glucose metabolism [6]. Obstructive sleep apnea is insidious and patients are often unaware of the associated symptoms. Cardinal manifestations include loud snoring, witnessed breathing pauses during sleep, fitful sleep quality, and excessive daytime sleepiness. Early recognition and appropriate therapy can ameliorate the neurobehavioral consequences and may also have favorable effects on cardiovascular health [7]. Habitual snoring is associated with hypertension, cerebrovascular disease and coronary heart disease [8, 9]. The prevalence of snoring among adults varies from different part of the world from 5 to 44% [8, 10, 11]. In a report from Abuja, Nigeria, overall prevalence of snoring among adults was 31% while the prevalence of clinically Suspected Obstructive Sleep Apneas (CSOSA) was 1%, (1.9% in males, 0.5% in females) [11].

The Epworth Sleepiness Scale (ESS) was used to determine excessive day time sleepiness. It is an eight item self administered questionnaire. Possible score ranges were from 0 to 24. For this study, an ESS score of more than 11 was taken to mean Excessive day time sleepiness EDS. The Berlin Questionnaire was used to identify the risk of having clinical obstructive sleep apnoea. The questionnaire consists of 3 categories related to the risk of having sleep apnea. Patients can be classified into High Risk or Low Risk based on their responses to the individual items and their overall scores in the symptom categories. Subjects were categorized as high risk for having OSA if there were 2 or more Categories where the score was positive and low risk if there was only 1 or no Categories where the score was positive [12]. The Berlin questionnaire has been documented to be clinically sensitive and correlates significantly with the presence of OSA among various populations. Clinically Suspected Obstructive Sleep Apneas (CSOSA) was defined in accordance with the 2001 International Classification of Sleep Disorders [13].

Table 2 shows the demographic parameters between hypertensive subjects with reported history of snoring and non-snorers. The mean age of snorers was significantly higher than non-snorers (59.4±12.1vs. 56.1±11.9, p< 0.05 respectively). Likewise, systolic blood pressure and fasting blood sugar were significantly higher among snorers than non snorers (141.9±21.2, 5.90±1.0 vs. 134.9±14.1, 4.9±1.8, p<0.05 respectively). Mean Epworth sleepiness scale was significantly higher among snorers than non-snorers (8.74±3.9 vs. 7.1±4.7, p<0.05 respectively) reflecting an increased daytime somnolence among snorers. Almost all snorers were found to have a high risk of OSA using the Berlin score compared to only 4% of non snorers.

The prevalence of snoring based on age group is shown in Table 3. The highest prevalence of snoring was found in the sixth decade followed by those more than 70 years. Snoring was also found to be commoner among overweight and obese hypertensive subjects as shown in Table 3.

Individuals with OSA have been shown to have heightened sympathetic activity due to activation of chemoreceptors leading to peripheral vasoconstriction [15]. OSA also results in the production of important neurohumoral mediators of cardiac and vascular disease [16]. Individuals with OSA have increased production of the potent vasoconstrictor endothelin and impaired endothelial function, which affect vasomotion. OSA has also been associated with systemic inflammation, reflected by increases in C-reactive protein and serum amyloid A levels, which may advance atherosclerosis and is associated with increased cardiovascular risk. Perhaps through its effects on sympathetic activity or because of sleep deprivation, OSA may increase insulin resistance, which promotes cardiovascular risk via multiple pathways [17]. Also, OSA is associated with increased levels of leptin, a hormone secreted by fat cells that is also associated with cardiovascular events.

This study also revealed that hypertensive subjects with positive history of snoring were significantly older than those without history of snoring. Furthermore, body mass index and fasting blood sugar were significantly higher among hypertensive subjects with history of snoring than those without it. This highlights the fact that hypertensive subjects with OSA likely have increased cardiovascular risk. The prevalence of snoring increased with increasing age group with the highest incidence among those in the sixth decade and the very elderly group (>70 years).This agrees with other studies have shown that obstructive sleep apnoea and snoring are directly related to age. With advancing age, sleep-related difficulties become increasingly common and often manifest as subjective complaints of difficulty falling asleep, reduced duration of night-time awakenings, and the amount of night-time sleep obtained [18, 19]. Mechanisms proposed for the age-related increase inprevalence include increased deposition of fat in the parapharyngeal area, lengthening of the softpalate, and changes in body structures surrounding the pharynx [20, 21].

Several epidemiologic studies have described the higher incidence of snoring and sleep apnoea among men compared to their female counterparts. Several explanation account for this: first, women may be less likely to report classical symptoms such as loud snoring, apnoea, nocturnal sorting or gasping [22, 23]. Secondly, differential response of the bed partner to the symptoms of obstructive breathing during sleep may also contribute to the clinical underrecognition of the disorder in women.