Results
A total of 1643 studies underwent screening, of which 1543 studies were subsequently excluded by title, abstract and full text in some papers. Out of the 100 studies, four papers could not be retrieved. Of the remaining 96 studies, 71 studies were excluded for various reasons, including not being RCTs (n=4), showing only protocol RCTs (n=5), not reporting the results in English or Thai (n=1), having participants younger than 60 years old (n=50), having additional interventions in both the control and intervention groups (n=3), having additional interventions solely in the intervention group (n=1), and having additional interventions only in the control group (n=1). Four studies did not report PSQI scores as an outcome. One study reported only the percentage change in PSQI. Additionally, there was one duplicate study. The search and study selection process is illustrated in figure 1 using a flow diagram.
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PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 flow diagram for new systematic reviews, which included searches of databases, registers and other sources. PSQI, Pittsburgh Sleep Quality Index; RCT, randomised controlled trial.
Risk of bias assessment
The risk of bias in the outcome was categorised according to the analysis approach, specifically the intention-to-treat group and the per-protocol group. Within the intention-to-treat group, 43.8% of studies had a low risk of bias, as shown in online supplemental figure S1. Subsequently, this was followed by studies with a high risk of bias at 31.3% and studies with some concern for bias at 25%. The main determinant of the high risk of bias was the measurement of outcomes by an unblinded assessor. Among the per-protocol group, 55.6% were categorised as low risk, whereas 22.2% were individually identified as having some concern and high risk (online supplemental figure S2). The primary contributory factors in concern and high-risk groups were unidentified randomisation techniques, concealment and measurement methods.
Study characteristics
This study incorporated a total of 25 studies undertaken between 1996 and 2021, encompassing 2170 participants. The most prevalent areas of study originated in Asia (56%), North America (16%), South America (16%) and European countries (12%). The majority of studies (80%) were conducted in community settings, whereas only 20% were carried out in nursing homes. The mean age of the participants was 70.38 (±4.56) years. The mean percentage of female participants was 71.85 (±21.86). The majority of patients were selected based on symptomatic criteria. Only one study had been carried out by recruiting participants based on the DSM-V criteria. Combination exercise, consisting of aerobic, strengthening, balancing or flexibility exercises, was the most prevalent form of exercise intervention, accounting for 48.15% of the total. Aerobic exercise alone accounted for 14.81%. The major level of exercise intensity was mild to moderate/moderate, accounting for 54.55% of the total reported studies. The average duration per session was approximately 53.69 (±11.79) minutes, and the number of sessions was three times per week (48%) and two times per week (35%). The average exercise duration per session was 150.65 (±70) minutes per week, and the exercise programme lasted for 14.4 weeks (±6.25). All participants in the study stated a compliance rate of 70% or above, as indicated by their self-reports (60%). The baseline GPSQI scores in the exercise and control groups were 8.37 (±2.38) and 8.27 (±2.16), respectively.
The characteristics of the included studies are outlined in online supplemental table S1.
Primary outcome
A total of 24 studies, with a sample size of 2045 participants, incorporated global PSQI scores as a measure of outcomes. Two treatment comparisons yielded a significant number of studies to conduct pairwise meta-analyses. The first comparison was aerobic exercise alone versus routine physical activity, with a total of four studies and 341 participants. The second comparison involved combination exercise versus routine physical activity, with a total of 13 studies and 1155 participants. A detailed summary of the global PSQI scores is presented in online supplemental table S2.
The direct meta-analysis demonstrated that the combination exercise had a significant impact on reducing GPSQI scores (USMD −2.35, 95% CI −3.13 to −1.57, p<0.001), but the studies had notable heterogeneity (I2=69.13%) (figure 2). It was found that the variation in exercise intensity may be responsible for the observed heterogeneity, and this subsequently reduced the degree of heterogeneity to 0% (figure 3). Low to moderate-intensity exercise appeared to decrease USMDs the most (USMD −1.91, 95% CI −3.14 to −0.68).
Pooled mean difference of Global Pittsburgh Sleep Quality Index (GPSQI) when comparing combination exercise with routine physical activity.
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Pooled mean difference of Global Pittsburgh Sleep Quality Index (GPSQI) when comparing combination exercise with routine physical activity according to intensity.
The comparison between aerobic exercise alone and routine physical activity also showed a significant decrease in GPSQI scores (USMD −4.36, 95% CI −7.86 to −0.86, p=0.01). However, the heterogeneity was also remarkable (I2=97.83%) (figure 4). The heterogeneity was reduced after accounting for time, duration, length and baseline GPSQI scores. The group with a session duration of less than 60 min had a substantial decrease in scores (USMD −2.07, 95% CI –2.55 to −1.58). Likewise, the group that had a session duration of 60 min or more also exhibited a notable decrease in scores (USMD −6.34, 95% CI −11.56 to −1.13), as depicted in online supplemental figure S3. There were significant decreases in scores among various subgroups, including those who performed more than 100 min of exercise per week (USMD −2.75, 95% CI −4.23 to −1.28), those who exercised for less than 10 weeks (USMD −2.75, 95% CI −4.23 to −1.28), those who exercised for 10 weeks or more (USMD −9.01, 95% CI −10.06 to −7.96), those with a baseline GPSQI score below 10 (USMD −2.75, 95% CI −4.23 to −1.28), along with those with a baseline GPSQI score of 10 or higher (USMD −9.01, 95% CI −10.06 to −7.96). The aforementioned findings are shown in online supplemental figures S4 to S6.
Pooled mean difference of Global Pittsburgh Sleep Quality Index (GPSQI) when comparing aerobic exercise with routine physical activity group.
Network meta-analysis
The network meta-analysis incorporated 24 out of 25 studies, as one study38 did not report the standard deviation of GPSQI scores. The studies included in the analysis comprised seven different interventions: aerobic exercise, strengthening, a combination of aerobic exercise and strengthening, a combination of strengthening and balancing exercises, a combination of strengthening and flexibility exercises, a combination of aerobic exercise, strengthening, balance exercises and flexibility exercises, as well as sleep education. The data indicated that there was no significant inconsistency across all trials, as indicated by a χ2 value of 3.78 and a p-value =0.58. The network graph showed that the pairs of combination verus routine, aerobic versus routine, and strengthening versus routine consisted of the largest number of studies. Meanwhile, the graph showed that the largest sample size was the routine activity group, followed by a combination of exercise and aerobic exercise, as shown in figure 5. Aerobic exercise demonstrated a substantial decrease in GPSQI scores when compared with regular physical activity (USMD−3.76, 95%CI −5.67 to –1.85), although the meta-analysis of the aerobic exercise group was characterised by marked heterogeneity (I2=97.83%). Strengthening exercises resulted in a substantial decrease in GPSQI scores compared with regular activity (USMD −5.75, 95% CI −8.06 to –3.45), combined exercise (USMD −3.21, 95% CI −5.73 to –0.70), and a combination of aerobic and strengthening exercise (USMD−4.28, 95% CI −8.35 to –0.22). The combination exercise, as compared with normal activity, resulted in a substantial reduction in GPSQI scores (USMD −2.54, 95% CI −3.65 to –1.43). Nevertheless, the meta-analysis of the combination exercise group was characterised by notable heterogeneity (I2=69.13%). Sleep education resulted in a substantial decrease in GPSQI scores compared with routine activity (USMD −4.63, 95% CI −7.12 to –2.15), as seen in table 1. Strengthening exercise was the most effective approach for reducing GPSQI, followed by sleep education and engaging in aerobic exercise, as seen in table 2 and online supplemental figure S7. The adjusted funnel plot demonstrated an overall symmetrical distribution of data across all studies, with the exception of one study39 suggesting a potential risk of publication bias as shown in online supplemental figure S8.
Table 1
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Estimation of mean difference (95% CI) comparison of GPSQI in upper triangle
Table 2
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Surface under the cumulative ranking curve of GPSQI
Network diagrams of Global Pittsburgh Sleep Quality Index (GPSQI) in all comparisons.
Secondary outcome
The secondary outcome of this study covered all seven domains of PSQI, comprising subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbance, usage of sleep medicine, and daytime dysfunction.
This research included only trials with combination exercise in the meta-analysis because sufficient numbers of eligible trials were not available for the other exercise types. The meta-analysis indicated the beneficial impact of combination exercise on reducing the five domains of PSQI scores in comparison to the routine physical activity group. The domains mentioned were sleep quality (USMD −0.43, 95% CI -0.67 to −0.2, p<0.001, I2=54.2%), sleep latency (USMD −0.44, 95% CI -0.76 to −0.12, p=0.01, I2=70.59%), sleep duration (USMD −0.43, 95% CI –0.6 to −0.26, p<0.001, I2=45.09%), sleep efficiency (USMD −0.39, 95% CI –0.58 to −0.2, p<0.001, I2=50.85%), and sleep medication (USMD −0.53, 95% CI –0.85 to −0.2, p=0.00, I2=56.58%). Nevertheless, the combination exercise group was not able to decrease their PSQI scores in the domains of sleep disturbance (USMD −0.15, 95% CI –0.39 to 0.08, p=0.2, I2=74.93%) and daytime dysfunction (USMD −0.29, 95% CI –0.62 to 0.04, p=0.09, I2=80.35%) compared with the group that performed regular physical activity. The aforementioned findings are shown in online supplemental figure S9A to S9G.
After performing a subgroup analysis on the sleep quality domain, it revealed that both the duration of exercise per session (<60 min and ≥60 min) and the weekly exercise duration (≤100 min and >100 min) resulted in improved sleep quality scores in the combination exercise group. Online supplemental figures S10A, S10B illustrate these findings.
In the domain of sleep latency, the subgroup analysis based on the baseline GPSQI score, percentage of female participants, time per session, and weekly exercise duration likewise revealed a decrease in sleep latency scores among the combination exercise group (online supplemental figures S11A-S11D). The duration of exercise per week (≤100 min and >100 min) both demonstrated the improvement in sleep efficiency scores (online supplemental figure S12). The subgroup analysis, which examined the female percentage, time per exercise session, duration per week, and baseline GPSQI scores of the sleep duration and sleep medication domains, revealed significant improvement in these scores among participants in the combination exercise group (online supplemental figure S13A–D,S15A–D). The length of the study may account for the variations in the sleep disturbance domain (I2=37.02%): studies lasting 1–12 weeks exhibited a reduction in sleep disturbance scores (USMDs −0.35, 95% CI –0.46 to −0.23), whereas studies lasting 13–30 weeks showed an increase in scores (USMD 0.15, 95% CI –0.08 to 0.38) (online supplemental figure S14).
The daytime dysfunction domain in older people aged 60–70 who undertook combination exercise compared with routine physical activity was improved; however, the benefit was not seen in people older than 70 years (online supplemental figure S16A). Similar outcomes were observed in the domain of daytime dysfunction. For studies lasting 1–12 weeks, the combination exercise group showed an improvement in daytime dysfunction scores (USMD −0.43, 95% CI –0.7 to −0.15). However, for studies lasting 13–30 weeks, there was no significant difference between the two groups (USMD −0.09, 95% CI –0.86 to 0.69) (online supplemental figure S16B).
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