3.2. Literature Reporting Changes in Objective Sleep Measures
Objective sleep measures are presented in
Table S3. Two twin studies identified an increase in REM sleep in ME/CFS patients compared to their healthy twin [
16,
17]. One article reported significantly reduced REM to non-REM sleep stage transitions [
30]. Alteration of transition patterns resulting in greater relative transition frequency was also observed [
30]. Sleep onset latency (SOL) was investigated in 13 articles [
9,
14,
17,
19,
21,
22,
23,
24,
25,
26,
27,
28,
31]. All 13 papers reported no differences in SOL between the ME/CFS patients and the HC [
9,
14,
17,
19,
21,
22,
23,
24,
25,
26,
27,
28,
31]. Non-REM sleep stages, (NREM) including stage 1- 4 sleep, % was investigated in 12 studies [
9,
14,
15,
16,
17,
19,
21,
22,
25,
26,
29,
31]. Two of the 12 studies reported increased stage 3 sleep, % [
16,
22]. All other findings were insignificant [
9,
14,
15,
17,
19,
21,
25,
26,
29,
31]. There were 11 studies that investigated slow-wave sleep (SWS) duration [
9,
14,
15,
21,
22,
23,
24,
25,
28,
29,
31]. From these studies, only three found that SWS in ME/CFS was significantly longer in duration compared to HC [
24,
25,
28]. The remaining studies reported no difference between the two groups [
9,
14,
15,
21,
22,
23,
29,
31].
When assessing sleep apnoea characteristics, five studies detected no differences in AHI [
14,
15,
21,
22,
23]. Three studies detected differences in AHI [
16,
24,
31]. MAI was measured in five studies [
14,
23,
24,
25,
31]. An increase of MAI in ME/CFS patients was found in all the studies [
14,
23,
24,
25,
31].