Table 1.

Participant demographics (n = 3,022).

Measure	n (%) or median (interquartile range)
Age (years)
17–24	468 (16%)
25–29	647 (21%)
30–34	683 (23%)
35–39	662 (22%)
40–44	555 (18%)
Height (m)
< 1.60	555 (18%)
1.60–1.69	1,544 (51%)
1.70–1.79	819 (27%)
≥ 1.80	98 (3%)
Body mass (kg)
< 60	519 (17%)
60–69	1,133 (38%)
70–79	803 (27%)
80–89	365 (12%)
≥ 90	193 (6%)
Ethnicity
White	2,824 (94%)
Black/African/Caribbean	81 (3%)
Asian	20 (1%)
Mixed/Multiple ethnicities	63 (2%)
Other	8 (< 1%)
Smokers	228 (8%)
Hormonal contraceptive users	1,424 (47%)
Pregnant	138 (5%)
Service
Army	1,341 (45%)
Royal navy	554 (18%)
Royal air force	1,118 (37%)
Rank
Junior non-commissioned officer and below	1,235 (41%)
Senior non-commissioned officer	729 (24%)
Junior officer	597 (20%)
Senior officer	446 (15%)
Job role
Combat	141 (5%)
Combat support	1,024 (34%)
Combat service support	1,855 (61%)
Regular or reserve service
Regular	2,802 (93%)
Reserve	201 (7%)
Length of service (years)
≤ 5	937 (31%)
6–10	648 (21%)
11–15	597 (20%)
16–20	(6%)
> 20	370 (12%)
Career deployments	2 (1, 5)
Typical sleep duration (hours)
≤ 5	353 (12%)
6–7	1,983 (66%)
≥ 8	680 (23%)

Missing data: Service, n = 9; Age (years), n = 7; Height (m), n = 6; Body Mass (kg), n = 9; Ethnicity, n = 26; Smokers, n = 3; Current Hormonal Contraceptive User, n = 11; Currently Pregnant, n = 33; Rank, n = 15; Job Role, n = 2; Regular or Reserve Service, n = 19; Length of Service (Years), n = 1; Number of Career Deployments, n = 20; Typical Sleep Duration (hours), n = 6.

Data are n (%) or median (interquartile range).