Nocturnal sweating--a common symptom of obstructive sleep apnoea: the Icelandic sleep apnoea cohort

Abstract

Objectives: To estimate the prevalence and characteristics of frequent nocturnal sweating in obstructive sleep apnoea (OSA) patients compared with the general population and evaluate the possible changes with positive airway pressure (PAP) treatment. Nocturnal sweating can be very bothersome to the patient and bed partner.

Design: Case-control and longitudinal cohort study.

Setting: Landspitali-The National University Hospital, Iceland.

Participants: The Icelandic Sleep Apnea Cohort consisted of 822 untreated patients with OSA, referred for treatment with PAP. Of these, 700 patients were also assessed at a 2-year follow-up. The control group consisted of 703 randomly selected subjects from the general population.

Intervention: PAP therapy in the OSA cohort.

Main outcome measures: Subjective reporting of nocturnal sweating on a frequency scale of 1-5: (1) never or very seldom, (2) less than once a week, (3) once to twice a week, (4) 3-5 times a week and (5) every night or almost every night. Full PAP treatment was defined objectively as the use for ≥4 h/day and ≥5 days/week.

Results: Frequent nocturnal sweating (≥3× a week) was reported by 30.6% of male and 33.3% of female OSA patients compared with 9.3% of men and 12.4% of women in the general population (p<0.001). This difference remained significant after adjustment for demographic factors. Nocturnal sweating was related to younger age, cardiovascular disease, hypertension, sleepiness and insomnia symptoms. The prevalence of frequent nocturnal sweating decreased with full PAP treatment (from 33.2% to 11.5%, p<0.003 compared with the change in non-users).

Conclusions: The prevalence of frequent nocturnal sweating was threefold higher in untreated OSA patients than in the general population and decreased to general population levels with successful PAP therapy. Practitioners should consider the possibility of OSA in their patients who complain of nocturnal sweating.

Keywords: Hypertension < Cardiology.

Figure 1

The study cohorts.

Figure 2

The prevalence of frequent nocturnal sweating (≥3× week) for subjects in the general population and the untreated obstructive sleep apnoea (OSA) patient cohort, divided by gender and age groups. Significant differences (p<0.05) are shown by an asterisk (*).

Figure 3

The distribution of reported nocturnal sweating (%) on a 1–5 frequency scale for the general population and untreated obstructive sleep apnoea (OSA) cohort. Additionally, the full positive airway pressure (PAP) users at the 2-year follow-up in the OSA cohort are shown. Subjects with frequent nocturnal sweating were defined by a prevalence ≥3× a week, as shown by the broken line.

Figure 4

The percentage of obstructive sleep apnoea (OSA) patients who reported no frequent sweating (≥3× week) at both baseline and follow-up, those who developed sweating and had persistent sweating between baseline and follow-up, as well as those with decreased sweating (≤2× a week). The results are shown separately for non-users, partial positive airway pressure (PAP) users and full PAP users. The change in reported frequent nocturnal sweating was significantly different between the three PAP groups (p<0.001).