Table 1

Exposure variables at baseline
Category Variables and response categories Men N = 1458 Women N = 2705
n % n %
Computer use (CU)
Low <2 hours per day 382 26 993 37
Medium 2–4 hours per day 505 35 950 35
High >4 hours per day 564 39 748 28
Email/chat use
Low Not at all 120 8 162 6
<1 hour per day 906 62 1732 64
Medium 1–2 hours per day 277 19 558 21
High >2 hours per day 151 10 236 9
Computer gaming
Low Not at all 655 45 2050 76
<1 hour per day 427 29 468 17
Medium 1–2 hours per day 204 14 114 4
High >2 hours per day 168 12 61 2
CU without breaks
Low Never 202 14 565 21
Only occasionally 314 22 832 31
Medium A few times per month 247 17 526 20
A few times per week 324 22 445 17
High Almost every day 366 25 323 12
CU causing lost sleep
Low Never 410 28 1128 42
Only occasionally 490 34 920 34
Medium A few times per month 316 22 393 15
High A few times per week 181 12 206 8
Almost every day 57 4 46 2
Mobile phone use
Low 0–5 calls + 0–5 SMSs per day 804 55 1433 53
Medium 0–5 calls + 6–10 SMSs, or vice versa 326 22 616 23
High >11 calls and/or >11 SMSs, or 323 22 645 24
6–10 calls + 6–10 SMSs per day

Frequencies and percentages in exposure variables, including categorizations into low, medium, and high, are presented. Missing values (non-responses to items) are not accounted for, which means that the n varies for the variables.

Questionnaire items: Computer use (CU): On average, how much time per day have you used on a computer (total use)? Email/chat use: On average, how much time per day have you used on a computer for emailing and chatting (leisure/private use)? Computer gaming: On average, how much time per day have you spent on computer gaming (e.g., computer games or online games, private/leisure use)? CU without breaks: How often have you used a computer for more than 2 hours without taking a break longer than 10 minutes? CU causing lost sleep: How often have you lost sleep because of sitting late at night at the computer? Mobile phone use: How many mobile phone calls on average have you made and received per day?, and How many SMS messages on average have you sent and received per day? The time span for all items was “over the past 30 days”.

Thomée et al.

Thomée et al. BMC Psychiatry 2012 12:176   doi:10.1186/1471-244X-12-176

Open Data