5.8Sleep

Sleeping pattern and daytime sleepiness are measures which were included at follow up only.

5.8.1Sleeping pattern

Participants’ ratings of their sleeping pattern in the previous two weeks are shown in Table 41. Relative to the comparison group, Gulf War veterans were significantly more likely to report difficulty falling asleep. The difference between the two groups increased with increasing severity of this sleeping pattern difficulty. Gulf War veterans were also significantly more likely than the comparison group to report moderate, severe or very severe difficulty in staying asleep. Further, Gulf War veterans were significantly more likely than the comparison group to report moderate problems with waking up early.

Table 41 Sleeping pattern in the two weeks prior to follow up

Sleep quality / Gulf War veterans N=692 / Comparison group N=652
n (%) / n (%) / RR* / Adj RR* (95% CI)
Difficulty falling asleep
None / 313 (45.23) / 373 (57.21) / 1.00 / 1.00
Mild / 218 (31.50) / 174 (26.69) / 1.49 / 1.51 (1.16-1.95)
Moderate / 113 (16.33) / 79 (12.12) / 1.70 / 1.57 (1.12-2.20)
Severe/very severe / 48 (6.94) / 26 (3.99) / 2.20 / 1.78 (1.07-2.97)
Difficulty staying asleep
None / 228 (32.81) / 253 (38.69) / 1.00 / 1.00
Mild / 206 (29.64) / 210 (32.11) / 1.09 / 1.09 (0.83-1.43)
Moderate / 168 (24.17) / 134 (20.49) / 1.39 / 1.37 (1.02-1.85)
Severe/very severe / 93 (13.38) / 57 (8.72) / 1.81 / 1.66 (1.12-1.85)
Problem waking up early
None / 334 (48.34) / 349 (53.86) / 1.00 / 1.00
Mild / 159 (23.01) / 170 (26.23) / 0.98 / 0.99 (0.75-1.30)
Moderate / 125 (18.09) / 82 (12.65) / 1.59 / 1.56 (1.12-2.16)
Severe/very severe / 73 (10.56) / 47 (7.25) / 1.62 / 1.45 (0.97-2.18)

* These RRs and the associated 95% CIs were calculated using multinomial logistic regression

5.8.2Daytime sleepiness

Figure 21 shows the pattern of scores achieved on the Epworth Sleepiness Scale50 for daytime sleepiness at follow up. From a total score range of 0-24, where higher scores indicate greater daytime sleepiness, the Gulf War veterans’ mean score was 7.13 (sd 4.57) whilst the mean score for the comparison group was 6.52 (sd 4.17). This difference in mean scores between groups did not reach statistical significance; adj mean diff 0.61, 95% CI 0.14 – 1.09 (not tabulated). Both groups had the same median score of 6.

Figure 21 Pattern of scores achieved on the Epworth Sleepiness Scale for daytime sleepiness

However, Figure 21 also shows that Gulf War veterans were more likely to achieve scores at the severe end of the scale than the comparison group. For example, 4.74% of Gulf War veterans and 2.44% of comparison group participants achieved a score greater than 16, which Johns (1991)50 observed only in patients with narcolepsy, idiopathic hypersomnia or moderately severe obstructive sleep apnoea. This difference between the two groups, in the proportion scoring 16 or above, is statistically significant; adj RR 1.91 95% CI 1.04-3.48 (not tabulated).

5.8.3Sleep apnoea

Sleep apnoea was included as one of the medical conditions that participants could report being diagnosed with, or treated for by a medical doctor, in the time since the baseline study (January 2001). At follow up, 70 (10.23%) Gulf War veterans and 63 (9.68%) comparison group participants reported sleep apnoea. This difference between groups did not reach statistical significance; RR 1.06, adj RR 1.04 (95% CI 0.75-1.45).

5.8.4Key findings

At the time of the follow up study, Gulf War veterans were significantly more likely than the comparison group to report difficulty falling asleep, difficulty staying asleep and problems with waking early. The general level of daytime sleepiness was similar between the two study groups, however very severe daytime sleepiness was more likely amongst Gulf War veterans than comparison group participants. Doctor diagnosed sleep apnoea was similarly reported in the two groups.

Australian Gulf War Veterans’ Follow Up Health Study: Technical Report 2015 Page 1