Table 1

Characteristics of study sample according to nap frequency, CoLaus study, Lausanne, Switzerland (n=3462)

No napNap frequencyP value
1–2 weekly3–5 weekly6–7 weekly
No (%)2014 (58.1)667 (19.3)411 (11.9)370 (10.7)
Age (years) (mean±SD)56.5 (10.2)53.9 (9.1)59.6 (9.9)63.1 (10.3)<0.001
Men (n (%))843 (41.9)303 (45.4)205 (49.9)208 (56.2)<0.001
Educational status (n (%))<0.001
 High472 (23.4)195 (29.2)87 (21.2)49 (13.2)
 Middle536 (26.6)195 (29.2)125 (30.4)84 (22.7)
 Low1006 (50.0)277 (41.5)199 (48.4)237 (64.1)
Smoker (n (%))372 (18.5)164 (24.6)82 (20.0)73 (19.7)0.008
Sedentary behaviour (n (%))1123 (55.8)379 (56.8)235 (57.2)233 (63.0)0.084
BMI (n (%))<0.001
 Normal1008 (50.1)321 (48.1)170 (41.4)125 (33.8)
 Overweight740 (36.7)249 (37.3)170 (41.4)157 (42.4)
 Obese266 (13.2)97 (14.5)71 (17.3)88 (23.8)
Sleep duration (hours/night) (mean±SD)6.9 (1.1)6.9 (1.1)7.1 (1.2)7.1 (1.2)0.010
Hypertension (n (%))720 (35.8)207 (31.1)181 (44)207 (56.0)<0.001
Diabetes (n (%))148 (7.4)52 (7.8)50 (12.2)65 (17.6)<0.001
Dyslipidaemia (n (%))286 (14.2)82 (12.3)82 (20.0)102 (27.6)<0.001
Excessive daytime sleepiness (ESS >10)† (n (%))160 (8.3)86 (13.5)56 (14.4)46 (13.0)<0.001
Severity of sleep apnoea‡ (n (%))<0.001
 Normal314 (33.1)103 (31.6)50 (26.0)32 (16.8)
 Mild333 (35.1)122 (37.4)76 (39.6)60 (31.4)
 Moderate193 (20.3)67 (20.6)31 (16.2)58 (30.4)
 Severe110 (11.6)34 (10.4)35 (18.2)41 (21.5)
 Depressive status190 (10.1)84 (13.4)55 (14.4)75 (22.3)<0.001
  • P values from Pearson χ2 or ANOVA where appropriate.

  • †n=3300.

  • ‡n=1659. Normal: apnoea–hypopnoea index (AHI) <5/hour; mild: AHI between 5 and 15/hour; moderate: between 15 and 30/hour; severe: >30/hour.

  • ESS, Epworth sleepiness scale.