Table 2

Prevalence of different types of headache complaints among Norwegian nurses

	Frequent headache*	Migraine	Tension-type headache	Chronic headache†	Medication-overuse headache
	% (n)	% (n)	% (n)	% (n)	% (n)
Work schedule (n=1415–1459):	0.2‡, p=0.979	2.5‡, p=0.472	3.5‡, p=0.321	2.3‡, p=0.510	1.7‡, p=0.637
Day only	47.3 (140)	22.6 (65)	24.5 (71)	1.7 (5)	1.0 (3)
Two-shift rotation	48.7 (242)	20.3 (98)	26.1 (129)	3.2 (16)	1.6 (8)
Night shift only	47.5 (48)	16.3 (16)	29.0 (29)	2.0 (2)	2.0 (2)
Three-shift rotation	47.6 (269)	18.8 (103)	29.9 (165)	2.1 (12)	0.9 (5)
Night shifts last year (n=1489–1534):	3.4‡, p=0.180	3.3‡, p=0.188	6.9‡, p=0.032	0.4‡, p=0.813	1.1‡, p=0.578
0 night shifts	47.8 (292)	21.9 (130)	24.4 (147)	2.6 (16)	1.5 (9)
1–20 night shifts	44.6 (179)	18.0 (70)	30.0 (118)	2.0 (8)	0.8 (3)
>20 night shifts	50.8 (265)	18.1 (92)	30.9 (159)	2.3 (12)	1.2 (6)
Quick returns last year (n=1465–1511):	0.2‡, p=0.902	1.5‡, p=0.480	2.4‡, p=0.296	0.2‡, p=0.885	0.8‡, p=0.666
0 quick returns	47.4 (162)	22.1 (73)	24.8 (83)	2.1 (7)	1.2 (4)
1–20 quick returns	48.8 (186)	18.9 (70)	29.6 (111)	2.4 (9)	0.8 (3)
>20 quick returns	48.7 (384)	19.1 (146)	28.8 (224)	2.5 (20)	1.4 (11)
Shift work disorder (n=1521–1567):	36.9‡, p<0.0005	11.3‡, p=0.001	1.6‡, p=0.208	5.7‡, p=0.017	0.5‡, p=0.491
No	43.4 (494)	17.7 (197)	26.9 (301)	1.8 (20)	1.1 (12)
Yes	60.7 (260)	25.6 (104)	30.2 (127)	4.0 (17)	1.6 (7)
Insomnia disorder (n=1537–1585):	25.1‡, p<0.0005	10.1‡, p=0.001	0.0‡, p=0.983	9.7‡, p=0.002	15.6‡, p<0.0005
No	43.8 (474)	17.4 (184)	28.0 (297)	1.5 (16)	0.5 (5)
Yes	57.5 (289)	24.5 (118)	27.8 (138)	4.2 (21)	2.8 (14)

Significant findings are shown in bold.
*Headache ≥1 days per month.
†Headache >14 days per month.
‡Pearson Χ², with Yates’ correction for continuity when used in a 2×2 table.