The effects of a digital lifestyle intervention in patients with hypertension: Results of a pilot randomized controlled trial.

In this pilot study, the authors investigated the preliminary effectiveness of the digital lifestyle intervention, actensio (mementor DE GmbH), in treating arterial hypertension. Adults with arterial hypertension were randomly assigned to an intervention group (actensio + standard care) or a control group (waiting list + standard care) in a 1:1 ratio. Primary and secondary endpoints were assessed at baseline (t0) and 3 months post-randomization (t1). The primary endpoint was average systolic blood pressure, measured at home for 1 week. Secondary endpoints included patient engagement (measured using the "patient activation measure"; PAM-13), average diastolic blood pressure, and heart rate. All endpoints were analyzed using ANCOVA models, following an intention-to-treat approach, while adjusting for baseline values. Missing data were estimated using multiple imputation models. A total of N = 102 participants (f = 59, age = 52.94 ± 9.01) were randomized to either the intervention (IG; N = 52) or the control group (CG; N = 50), of which N = 80 completed the blood pressure diary, and N = 81 the PAM-13 at t1. Between-group comparisons showed an average group difference in systolic blood pressure of -5.06 mm Hg (95% CI = -8.71 to -1.41, p = .013) between the intervention group (M = 137.37 ± 10.13) and the control group (M = 142.35 ± 11.23). Average group difference for patient engagement was 3.35 points with a trend towards statistical significance (95% CI = -018 to 6.89, p = .064), favoring the intervention group (MIG = 79.38 ± 9.44 vs. MCG = 75.45 ± 10.62). There were no group differences in diastolic blood pressure (-1.78 mm Hg; 95% CI = -4.50 to 0.95, p = .402) and heart rate (-0.684; 95% CI = -3.73 to 2.36, p = 0.683). The results of the present pilot study confirm the preliminary effectiveness of the digital lifestyle intervention, actensio, in reducing high blood pressure in patients with hypertension.

Investigating the efficacy of digital cognitive behavioural therapy in comparison to a sleep-monitoring application via integrated diary and actigraphy: A randomised-controlled trial.

Dissemination of digital cognitive behavioural therapy is a promising approach for treating insomnia in the broad population. Current evidence supports the effectiveness of the digital format, but clinical findings are often limited by the choice of control group and lack of in-depth therapeutic measures. This study was designed to investigate the specific effects of digital cognitive behavioural therapy in comparison to a self-monitoring application. Participants meeting criteria for insomnia were randomly allocated (1:1) to 8 weeks of digital cognitive behavioural therapy or 8 weeks of digital sleep monitoring (control application). The primary outcome, insomnia severity, was assessed at baseline, 8- and 16-weeks post-randomisation. Secondary outcomes included the assessment of sleep via application-integrated sleep diaries and actigraphy. Linear-mixed models were fitted to assess between-group differences. Fifty-six participants (48 females, mean age: M = 45.55 ± 13.70 years) were randomised to either digital cognitive behavioural therapy (n = 29) or digital sleep monitoring (n = 27). At 8- and 16-weeks post-randomisation, large treatment effects (d = 0.87-1.08) indicated robust reductions (-3.70 and -2.97, respectively; p ≤ 0.003) in insomnia severity in the digital cognitive behavioural therapy arm, relative to digital sleep monitoring. Treatment effects in favour of digital cognitive behavioural therapy were also found for self-reported and actigraphy-derived sleep continuity variables, indicating that sleep improved throughout the 8-week intervention period. Our study reinforces the role of digital cognitive behavioural therapy in achieving clinical improvements for patients with insomnia, affirming previous findings and supporting the specific effects of cognitive behavioural therapy.

The effect of single-component sleep restriction therapy on depressive symptoms: A systematic review and meta-analysis.

Sleep restriction therapy is a behavioural component within cognitive behavioural therapy for insomnia and is an effective standalone treatment for insomnia, but its effect on depressive symptoms remains unclear. This review aimed to synthesise and evaluate the impact of single-component sleep restriction therapy on depressive symptoms relative to a control intervention. We searched electronic databases and sleep-related journals for randomised controlled trials and uncontrolled clinical trials, published from 1 January 1986 until 19 August 2023, that delivered sleep restriction therapy to adults with insomnia. Random-effects meta-analysis of standardised mean differences and Cochrane risk of bias assessment were performed on randomised controlled trials, while uncontrolled clinical trials were discussed narratively. The meta-analysis was pre-registered on PROSPERO (ID: CRD42020191803). We identified seven randomised controlled trials (N = 1102) and two uncontrolled clinical trials (N = 22). Findings suggest that sleep restriction therapy is associated with a medium effect for improvement in depressive symptoms at post-treatment (Nc = 6, g = -0.45 [95% confidence interval = -0.70 to -0.21], p < 0.001) and a small effect at follow-up (Nc = 4, g = -0.31 [95% confidence interval = -0.45 to -0.16], p < 0.001). Five of the seven included randomised controlled trials were judged to have a high risk of bias. Standalone sleep restriction therapy appears to be efficacious for improving depressive symptoms at post-treatment and follow-up. However, conclusions are tentative due to the small number of trials and because none of the trials was performed in a population with clinically defined depression. Large-scale trials are needed to test the effect of sleep restriction therapy in patients experiencing depression and insomnia. Findings also highlight the need to improve the standardisation and reporting of sleep restriction therapy procedures, and to design studies with more rigorous control arms to reduce potential bias.

The clinical effect of digital cognitive behavioural therapy for insomnia in subgroups with depressive and anxiety symptoms: A secondary analysis of a randomized-controlled trial.

Insomnia is a highly prevalent mental disorder, and is often co-occurring with depression and anxiety disorders. Cognitive behavioural therapy for insomnia as treatment of choice for insomnia can also be applied digitally (digital cognitive behavioural therapy for insomnia), making it more accessible. This is a secondary data analysis of a two-armed parallel randomized-controlled trial. In the primary publication, N = 238 participants meeting criteria for the 5th edition of Diagnostic and Statistical Manual of Mental Disorders chronic insomnia disorder were randomly assigned to either 8 weeks of digital cognitive behavioural therapy for insomnia + treatment-as-usual, or waitlist + treatment-as-usual. To determine the clinical effects of digital cognitive behavioural therapy for insomnia in populations with comorbid anxiety and depression symptoms, this secondary analysis focused on two subgroups: (1) participants with high initial depressive symptoms; and (2) participants with high initial anxiety symptoms. Symptoms of insomnia, depression and anxiety as primary outcome measures were obtained at baseline, 8 weeks post-randomization and, in the intervention group only, at 6- and 12-months follow-up. At 8 weeks post-randomization, the use of digital cognitive behavioural therapy for insomnia in both subgroups was associated with large reductions in insomnia severity in comparison to control (depression subgroup: d = 2.37; anxiety subgroup: d = 2.13). Between-group treatment effects were also observed for symptoms of depression in the depression subgroup (d = 1.59), and for symptoms of anxiety in the anxiety subgroup (d = 1.28). Within-group effects were stable over time (d = 0.64-1.63). This secondary analysis shows that digital cognitive behavioural therapy for insomnia reduces insomnia and comorbid symptoms in participants with high initial symptoms of either depression or anxiety with sustained long-term effects.

The effect of sleep restriction therapy for insomnia on REM sleep fragmentation: A secondary analysis of a randomised controlled trial.

Rapid eye movement sleep fragmentation is hypothesised to be a reliable feature of insomnia, which may contribute to emotion dysregulation. Sleep restriction therapy, an effective intervention for insomnia, has the potential to reduce rapid eye movement sleep fragmentation through its manipulation of basic sleep-wake processes. We performed secondary data analysis of a randomised controlled trial to examine whether sleep restriction therapy reduces rapid eye movement sleep fragmentation in comparison to a matched control arm. Participants (n = 56; 39 female, mean age = 40.78 ± 9.08 years) were randomly allocated to 4 weeks of sleep restriction therapy or 4 weeks of time in bed regularisation. Ambulatory polysomnographic recordings were performed at baseline, week 1 and week 4. Arousals during rapid eye movement and non-rapid eye movement sleep were scored blind to group allocation. The following rapid eye movement sleep fragmentation index was the primary outcome: index 1 = (rapid eye movement arousals + rapid eye movement awakenings + non-rapid eye movement intrusions)/rapid eye movement duration in hours. Secondary outcomes were two further indices of rapid eye movement sleep fragmentation: index 2 = (rapid eye movement arousals + rapid eye movement awakenings)/rapid eye movement duration in hours; and index 3 = rapid eye movement arousals/rapid eye movement duration in hours. A non-rapid eye movement fragmentation index was also calculated (non-rapid eye movement arousals/non-rapid eye movement duration in hours). Linear-mixed models were fitted to assess between-group differences. There was no significant group difference for the primary rapid eye movement fragmentation index at week 1 (p = 0.097, d = -0.31) or week 4 (p = 0.741, d = -0.06). There was some indication that secondary indices of rapid eye movement fragmentation decreased more in the sleep restriction therapy group relative to control at week 1 (index 2: p = 0.023, d = -0.46; index 3: p = 0.051, d = -0.39), but not at week 4 (d ≤ 0.13). No group effects were found for arousals during non-rapid eye movement sleep. We did not find clear evidence that sleep restriction therapy modifies rapid eye movement sleep fragmentation. Small-to-medium effect sizes in the hypothesised direction, across several indices of rapid eye movement fragmentation during early treatment, demand further investigation in future studies.

Nurse-delivered sleep restriction therapy in primary care for adults with insomnia disorder: a mixed-methods process evaluation.

BACKGROUND: Sleep restriction therapy (SRT) is a behavioural therapy for insomnia. AIM: To conduct a process evaluation of a randomised controlled trial comparing SRT delivered by primary care nurses plus a sleep hygiene booklet with the sleep hygiene booklet only for adults with insomnia disorder. DESIGN AND SETTING: A mixed-methods process evaluation in a general practice setting. METHOD: Semi-structured interviews were conducted in a purposive sample of patients receiving SRT, the practice nurses who delivered the therapy, and also GPs or practice managers at the participating practices. Qualitative data were explored using framework analysis, and integrated with nurse comments and quantitative data, including baseline Insomnia Severity Index score and serial sleep efficiency outcomes to investigate the relationships between these. RESULTS: In total, 16 patients, 13 nurses, six practice managers, and one GP were interviewed. Patients had no previous experience of behavioural therapy, needed flexible appointment times, and preferred face-to-face consultations; nurses felt prepared to deliver SRT, accommodating patient concerns, tailoring therapy, and negotiating sleep timings despite treatment complexity and delays between training and intervention delivery. How the intervention produced change was explored, including patient and nurse interactions and patient responses to SRT. Difficulties maintaining SRT, negative attitudes towards treatment, and low self-efficacy were highlighted. Contextual factors, including freeing GP time, time constraints, and conflicting priorities for nurses, with suggestions for alternative delivery options, were raised. Participants who found SRT a positive process showed improvements in sleep efficiency, whereas those who struggled did not. CONCLUSION: SRT was successfully delivered by practice nurses and was generally well received by patients, despite some difficulties delivering and applying the intervention in practice.

Clinical and cost-effectiveness of nurse-delivered sleep restriction therapy for insomnia in primary care (HABIT): a pragmatic, superiority, open-label, randomised controlled trial.

BACKGROUND: Insomnia is prevalent and distressing but access to the first-line treatment, cognitive behavioural therapy (CBT), is extremely limited. We aimed to assess the clinical and cost-effectiveness of sleep restriction therapy, a key component of CBT, which has the potential to be widely implemented. METHODS: We did a pragmatic, superiority, open-label, randomised controlled trial of sleep restriction therapy versus sleep hygiene. Adults with insomnia disorder were recruited from 35 general practices across England and randomly assigned (1:1) using a web-based randomisation programme to either four sessions of nurse-delivered sleep restriction therapy plus a sleep hygiene booklet or a sleep hygiene booklet only. There was no restriction on usual care for either group. Outcomes were assessed at 3 months, 6 months, and 12 months. The primary endpoint was self-reported insomnia severity at 6 months measured with the insomnia severity index (ISI). The primary analysis included participants according to their allocated group and who contributed at least one outcome measurement. Cost-effectiveness was evaluated from the UK National Health Service and personal social services perspective and expressed in terms of incremental cost per quality-adjusted life year (QALY) gained. The trial was prospectively registered (ISRCTN42499563). FINDINGS: Between Aug 29, 2018, and March 23, 2020 we randomly assigned 642 participants to sleep restriction therapy (n=321) or sleep hygiene (n=321). Mean age was 55·4 years (range 19-88), with 489 (76·2%) participants being female and 153 (23·8%) being male. 580 (90·3%) participants provided data for at least one outcome measurement. At 6 months, mean ISI score was 10·9 (SD 5·5) for sleep restriction therapy and 13·9 (5·2) for sleep hygiene (adjusted mean difference -3·05, 95% CI -3·83 to -2·28; p<0·0001; Cohen's d -0·74), indicating that participants in the sleep restriction therapy group reported lower insomnia severity than the sleep hygiene group. The incremental cost per QALY gained was £2076, giving a 95·3% probability that treatment was cost-effective at a cost-effectiveness threshold of £20 000. Eight participants in each group had serious adverse events, none of which were judged to be related to intervention. INTERPRETATION: Brief nurse-delivered sleep restriction therapy in primary care reduces insomnia symptoms, is likely to be cost-effective, and has the potential to be widely implemented as a first-line treatment for insomnia disorder. FUNDING: The National Institute for Health and Care Research Health Technology Assessment Programme.

The clinical effects of digital cognitive behavioral therapy for insomnia in a heterogenous study sample: results from a randomized controlled trial.

STUDY OBJECTIVES: Numerous studies worldwide have reported the beneficial effects of digital cognitive behavioral therapy for insomnia (dCBT-I). However, few focus on real-world study samples that reflect people in regular care. To test whether dCBT-I is suitable within German regular care, we designed a randomized controlled trial recruiting a heterogenous insomnia population. METHODS: Participants aged ≥18 who met the criteria for insomnia disorder were randomized to 8-weeks dCBT-I + care-as-usual (CAU) or they were set on a waitlist + CAU. The intervention group was followed-up at 6- and 12-months. The primary outcome was self-reported insomnia severity, assessed with the Insomnia Severity Index (ISI) at 8-weeks post-randomization. A one-way ANCOVA with baseline score as a covariate was fitted to determine group differences. Secondary outcomes included measures of daytime functioning, quality of life, depression, anxiety, dreams, and nightmares. RESULTS: Of the N = 238 participants (67.6% female), age range 19-81 years, n = 118 were randomized to dCBT-I and n = 120 to the control group. At posttreatment, the use of dCBT-I was associated with a large reduction in the ISI (Diffadj = -7.60) in comparison to WLC (d = -2.08). This clinical improvement was also reflected in responder and remission rates. Treatment effects were also observed for daytime functioning, quality of life, symptoms of depression and anxiety (ds = 0.26-1.02) and at long-term follow-up (intervention group only; ds = 0.18-1.65). No effects were found for dream and nightmare frequency. CONCLUSIONS: This study showed that dCBT-I reduces insomnia symptoms and improves daytime functioning in a heterogenous insomnia population in Germany with sustained long-term treatment effects in the intervention group. Our results underscore the potential of digital health applications, their suitability within regular care, and their role in facilitating widespread implementation of CBT-I as a first-line treatment for insomnia.

The effect of sleep restriction therapy for insomnia on sleep pressure and arousal: a randomized controlled mechanistic trial.

STUDY OBJECTIVES: Sleep restriction therapy (SRT) effectively treats insomnia but mechanisms are poorly understood. Theoretical models suggest that potentiation of sleep pressure and reduction of arousal are key mechanisms of action. To our knowledge, this has never been directly tested. We designed a randomized controlled trial with embedded mechanistic measurement to investigate if SRT causally modifies multidimensional assessments of sleep pressure and arousal. METHODS: Participants aged 25-55 who met DSM-5 diagnostic criteria for insomnia disorder were randomized to four weeks of SRT or time in bed regularization (TBR), a control intervention that involves prescription of a regular but not reduced time in bed. Sleep pressure was assessed through daily diary appraisal of morning and evening sleepiness, weekly Epworth sleepiness scale (ESS) scores, psychomotor vigilance, and non-rapid eye movement (NREM) delta power (0.75-4.5 Hz) from ambulatory polysomnographic recordings. Arousal was assessed through daily diary appraisal of cognitive arousal, the pre-sleep arousal scale (PSAS), and NREM beta power (15-32 Hz). Outcomes were assessed at baseline (2-week period prior to randomization), during the intervention phase (1-4 weeks post-randomization), and at 12-week follow-up. We performed intention-to-treat analyses using linear mixed models. For continuous daily measures, the treatment period was split into early (weeks 1-2) and late (weeks 3-4) treatment. RESULTS: Fifty-six participants (39 females, mean age = 40.78 ± 9.08) were assigned to SRT (n = 27) or TBR (n = 29). The SRT group showed enhanced sleep pressure relative to TBR, reflected in (1) enhanced sleepiness in the evening during early (d = 1.17) and late treatment (d = 0.92), and in the morning during early treatment (d = 0.47); (2) higher daytime sleepiness on the ESS at weeks-1 and -2 (d = 0.54, d = 0.45); and (3) reduced psychomotor vigilance at week-1 (d = 0.34). The SRT group also showed reduced arousal relative to TBR, reflected in lower levels of daily-monitored cognitive arousal during early treatment (d = 0.53) and decreased PSAS total score at week-4 and week-12 (ds ≥ 0.39). Power spectral analysis of all night NREM sleep revealed an increase in relative, but not absolute, EEG delta power at week-1 and week-4 (ds ≥ 0.52) and a decrease of relative EEG beta power at week-4 (d = 0.11). CONCLUSION: For the first time, we show that SRT increases sleep pressure and decreases arousal during acute implementation, providing support for mechanism-of-action.

The clinical effects of sleep restriction therapy for insomnia: A meta-analysis of randomised controlled trials.

Sleep restriction therapy (SRT) is an established treatment for insomnia that has been used in clinical practise for over 30 y. It is commonly delivered as part of multicomponent cognitive-behavioural therapy (CBT-I) but has also been linked to beneficial effects as a standalone intervention. In order to quantify the efficacy of SRT we performed a comprehensive meta-analysis of randomised controlled trials (RCTs) comparing SRT to minimally active or non-active control groups. Primary outcomes were self-reported insomnia severity and sleep diary metrics at post-treatment. Weighted effect sizes were calculated with Hedges' g and risk of bias was assessed by two independent raters with the Cochrane tool. Our search yielded eight RCTs meeting inclusion/exclusion criteria. Random effects models revealed large treatment effects in favour of SRT versus control for insomnia severity measured with the insomnia severity index (g = -0.93; 95% CI = -1.15, -0.71), sleep efficiency (g = 0.91; 95% CI = 0.52, 1.31), sleep onset latency (g = -0.62; 95% CI = -0.84, -0.40), and wake-time after sleep onset (g = -0.83; 95% CI = -1.11, -0.55). No effects were found for total sleep time (g = 0.02; 95% CI = -0.29, 0.34). Results should be interpreted in the context of the small number of comparisons (≤6 per outcome), high risk of bias (6 out of 8 studies met criteria for high risk), and heterogeneity in study design and SRT administration. Only a small number of studies provided outcomes at follow-up (n ≤ 3), hindering assessment of long-term effects. Sleep restriction therapy effectively improves insomnia severity and sleep continuity in the short term; more studies are needed to assess if effects are sustained at long-term follow-up (>3 m). Post-treatment effect sizes appear as large as multicomponent CBT-I. To reduce risk of bias, future studies should consider testing the effects of SRT against control groups that are matched for non-specific treatment effects. Large-scale pragmatic trials are also needed to test if SRT is effective in clinical practise and to quantify effects on daytime functioning and quality of life.

Reporting of adverse events in cognitive behavioural therapy for insomnia: A systematic examination of randomised controlled trials.

Adverse events are undesirable events that can occur during medical or psychological treatment. There has been limited attention to adverse events in psychological treatment trials relative to pharmacotherapy trials. Cognitive behavioural therapy (CBTI) is the first line treatment for insomnia but studies have reported potential negative effects during acute implementation. This review aimed to understand the extent to which adverse events are monitored for and reported in the CBTI trial literature. Ninety-nine randomised controlled trials were identified for inclusion, with findings showing that 32.3% (n = 32) of studies addressed adverse events in some way, while only 7.1% (n = 7) of studies met all criteria for adequate reporting of adverse events. For studies that reported on adverse events by group, there did not appear to be consistent differences between trial arms, however the limited evidence-base coupled with marked heterogeneity in monitoring and reporting makes it difficult to draw clear conclusions at this time. We outline recommendations for the field aimed at improving prospective monitoring and reporting of adverse events in psychological/behavioural treatment trials.

The acute effects of sleep restriction therapy for insomnia on circadian timing and vigilance.

Sleep-restriction therapy (SRT) has been shown to improve insomnia symptoms by restricting sleep opportunity. Curtailment of time in bed affects the duration and consolidation of sleep, but also its timing. While recent work suggests that people with insomnia are characterised by misalignment between circadian and behavioural timing of sleep, no study has investigated if SRT modifies this relationship. The primary aim of the present study was to examine change in phase angle after 2 weeks of SRT. As a secondary aim, we also sought to assess the effect of SRT on psychomotor vigilance. Following a 1-week baseline phase, participants implemented SRT for 2 consecutive weeks. Phase angle was derived from the difference between the decimal clock time of dim light melatonin onset (DLMO) and attempted sleep time. Secondary outcomes included vigilance (assessed via hourly measurement during the DLMO laboratory protocol), sleep continuity (assessed via sleep diary and actigraphy), and insomnia severity. Eighteen participants meeting insomnia criteria (mean [SD] age 37.06 [8.99] years) took part in the study. Consistent with previous research, participants showed robust improvements in subjective and objective sleep continuity, as well as reductions in insomnia severity. The primary outcome (phase angle) was measurable in 15 participants and revealed an increase of 34.8 min (~0.58 hr; 95% confidence interval [CI] 0.01-1.15) from baseline to post-treatment (mean [SD] 2.27 [0.94] versus 2.85 [1.25] hr). DLMO remained relatively stable (20:49 versus 21:01 hours), while attempted sleep was 46.8 min later (~0.78 hr; 95%CI 0.41-1.15; 23:05 versus 23:52 hours). For psychomotor vigilance, reaction time was delayed (by 52.71 ms, 95% CI 34.44-70.97) and number of lapses increased (by 5.84, 95% CI 3.93-7.75) after SRT. We show that SRT increases phase angle during treatment, principally by delaying the timing of sleep attempt. Future studies are needed to test if an increase in phase angle is linked to clinical improvement. Finally, reduction in vigilance after SRT appears to be of similar magnitude to normal sleepers undergoing experimental sleep restriction, reinforcing the importance of appropriate safety advice during implementation.

Isolating the role of time in bed restriction in the treatment of insomnia: a randomized, controlled, dismantling trial comparing sleep restriction therapy with time in bed regularization.

STUDY OBJECTIVES: Sleep restriction therapy (SRT) is one of the most effective treatments for insomnia. Restriction of time in bed (TIB) is assumed to be the central mechanism through which SRT improves sleep consolidation and reduces insomnia symptoms. This hypothesis has never been directly tested. We designed a randomized, controlled, dismantling trial in order to isolate the role of TIB restriction in driving both clinical and polysomnographic sleep outcomes. METHODS: Participants aged 25-55 who met diagnostic criteria for insomnia disorder were block-randomized (1:1) to 4 weeks of SRT or time in bed regularization (TBR), a treatment that involves the prescription of a regular but not reduced TIB. The primary outcome was assessed with the insomnia severity index (ISI) at baseline, 4-, and 12-weeks post-randomization. Secondary outcomes included sleep continuity (assessed via polysomnography, actigraphy, and diary) and quality of life. We performed intention-to-treat analyses using linear mixed models. RESULTS: Fifty-six participants (39 females, mean age = 40.78 ± 9.08) were assigned to SRT (n = 27) or TBR (n = 29). Daily monitoring of sleep via diaries and actigraphy confirmed large group differences in TIB (d range = 1.63-1.98). At 4-weeks post-randomization, the adjusted mean difference for the ISI was -4.49 (d = -1.40) and -4.35 at 12 weeks (d = -1.36), indicating that the SRT group reported reduced insomnia severity relative to TBR. Robust treatment effects in favor of SRT were also found for objective and self-reported sleep continuity variables (d range = 0.40-0.92) and sleep-related quality of life (d = 1.29). CONCLUSIONS: For the first time, we demonstrate that TIB restriction is superior to the regularization of TIB on its own. Our results underscore the centrality of the restriction component in reducing insomnia symptoms and consolidating sleep.

How does sleep restriction therapy for insomnia work? A systematic review of mechanistic evidence and the introduction of the Triple-R model.

For over 30 y sleep restriction therapy (SRT) has been used to treat insomnia but we know very little about how this therapy exerts its effects. When SRT was first described, it was hypothesised to treat insomnia by addressing four key factors: strengthening homeostatic sleep pressure, inhibiting perpetuating practices (excessive time in bed), attenuating hyperarousal and tightening regulatory control of sleep by the endogenous circadian pacemaker. We conducted a systematic literature review in search of evidence for these putative mechanisms-of-action. A total of 15 randomised and non-randomised studies investigating SRT met inclusion criteria. For each study, we extracted all variables associated with the proposed mechanisms and assessed study quality using a structured appraisal tool. The extracted variables were: time in bed (TIB), napping, variability in sleep, markers of circadian rhythmicity, measurements of sleep pressure/sleepiness, and assessments of arousal. Overall study quality was poor as indicated by a mean quality score of 17 (out of a possible range of 0-31). No study indicated, or indeed was designed to test, whether changes in the proposed mechanisms act as mediators of treatment outcomes. Of all reviewed studies, most reported a reduction in TIB (10/10) and/or revealed a decrease in sleep onset latency (10/14), indexing increased sleep pressure. However, such changes were most often reported at the end of treatment, reflecting an outcome and not a mechanism of SRT per se. Evidence for reduction in arousal (4/4) and night-to-night sleep variability (2/2) was found in only a small number of uncontrolled studies while there was no evidence for change in circadian phase or periodicity (0/1). Our review suggests that SRT targets some of the hypothesised processes but specifically-designed mechanistic evaluations are needed. We introduce a new testable model of SRT mechanism-of-action (Triple-R) and set out a research agenda aimed at stimulating prospective investigations.

A new face of sleep: The impact of post-learning sleep on recognition memory for face-name associations.

Sleep has been demonstrated to improve consolidation of many types of new memories. However, few prior studies have examined how sleep impacts learning of face-name associations. The recognition of a new face along with the associated name is an important human cognitive skill. Here we investigated whether post-presentation sleep impacts recognition memory of new face-name associations in healthy adults. Fourteen participants were tested twice. Each time, they were presented 20 photos of faces with a corresponding name. Twelve hours later, they were shown each face twice, once with the correct and once with an incorrect name, and asked if each face-name combination was correct and to rate their confidence. In one condition the 12-h interval between presentation and recall included an 8-h nighttime sleep opportunity ("Sleep"), while in the other condition they remained awake ("Wake"). There were more correct and highly confident correct responses when the interval between presentation and recall included a sleep opportunity, although improvement between the "Wake" and "Sleep" conditions was not related to duration of sleep or any sleep stage. These data suggest that a nighttime sleep opportunity improves the ability to correctly recognize face-name associations. Further studies investigating the mechanism of this improvement are important, as this finding has implications for individuals with sleep disturbances and/or memory impairments.