Sleep and Mood
Scott 2021 (meta-analysis, 65 trials) reports that improving sleep produced medium effects on composite mental health, depression, anxiety and rumination, and Takano 2023 reports CBT-I improved depression and anxiety in daytime workers; CBT-I's effect on depressive symptoms is reported as significant by Palagini 2024 and as a possible positive effect by Ballesio 2018.
- Loud snoring with witnessed gasping/choking or breathing pauses plus daytime sleepiness (possible obstructive sleep apnea), refer to a clinician
- Difficulty falling or staying asleep at least 3 nights/week for 3+ months with daytime impairment (possible chronic insomnia disorder), refer to a clinician
- Excessive daytime sleepiness despite adequate time in bed, or falling asleep involuntarily during activities, refer to a clinician
- Sleep problems accompanied by persistent low mood, hopelessness, or thoughts of self-harm, seek prompt professional support
What the evidence says
The sources on this entry are meta-analyses and trials of sleep interventions with mental-health outcomes, and syntheses linking sleep to depression and to glycaemic measures. Scott 2021 (meta-analysis, 65 randomised trials, 8608 participants) reports that improving sleep produced medium effects on composite mental health (g = -0.53), depression (-0.63), anxiety (-0.51) and rumination (-0.49), with smaller effects on stress and psychosis symptoms and a dose-response relationship, and concludes that sleep is causally related to mental health. Takano 2023 (meta-analysis, 21 studies) reports that CBT-I improved insomnia severity, depression (g = -0.37), anxiety (g = -0.35) and fatigue in daytime workers, with no improvement in total sleep time. Palagini 2024 (meta-analysis, 11 studies) reports CBT-I effective in reducing depressive symptoms and concludes that it may serve as a preventive strategy or early intervention against psychiatric disorders, particularly depression. Ballesio 2018 (network meta-analysis, 47 studies) reports a significant effect of individual face-to-face CBT-I on depressive symptoms (d = 0.34) but not on fatigue, with high heterogeneity, and concludes that it may have positive effects on daytime depressive symptoms. Boland 2023 (systematic review, 6 studies) reports that 4 of 6 studies found significantly lower onset of major depression with CBT-I than control, with the evidence overall favouring insomnia treatment reducing the risk of onset but methodological heterogeneity limiting firm conclusions. Kalkanis 2025 (systematic review, 59 studies) reports moderate-certainty evidence linking sleep-timing irregularity to higher depressive and anxiety symptoms. Two randomised trials are on the entry: McGrath 2017 reports that a web-delivered sleep intervention improved sleep quality and psychosocial health but did not reduce 24-hour blood pressure, and Baron 2019 reports a technology-assisted sleep extension intervention as feasible, with preliminary efficacy on sleep and blood pressure. On glycaemic outcomes, Mostafa 2025 (meta-analysis, 24 studies) reports that CBT-I and/or sleep hygiene significantly reduced HbA1c by 0.27%, and by 0.43% in type 2 diabetes, while Kothari 2020 (meta-analysis, 22 studies) reports improved sleep quality but non-significant reductions in HbA1c and fasting glucose, with effects on glucose metabolism mixed or inconclusive. This is general wellness information, not a diagnosis or treatment of any mental health condition.
- “Mood problems are unrelated to sleep.” Improving sleep produced medium effects on depression and anxiety across 65 trials.
- “Fixing sleep cures depression.” Improving sleep reduces depressive and anxiety symptoms with a medium effect; this app does not diagnose or treat mood disorders.
- Do not claim to diagnose, treat, or cure insomnia, sleep apnea, or any sleep disorder
- Do not promise guaranteed, instant, or permanent improvements in sleep
- Do not present these general hygiene techniques as clinical therapy (e.g., CBT-I) or a substitute for medical care
- Agreement
- Direction recorded for 0 of 10 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- A source states a certainty rating for 1 outcome.
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (10)
- What it measured
- Association between sleep regularity and mental, cardiometabolic, inflammatory, cognitive, lifestyle, and mortality outcomes
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review (narrative synthesis)
- Studies and participants, as stated
- 59 primary studies (from 3140 records; 147 full texts)
- What it measured
- Preventive effect of insomnia treatment (CBT-I) on depression onset
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- 6 studies (from 186)
- Heterogeneity, as stated
- Evidence overall favors insomnia treatment reducing risk of MDD onset, but methodological heterogeneity limits firm conclusions; more research warranted
- What it measured
- Effectiveness of CBT-I on insomnia symptoms in workers
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of RCTs
- Studies and participants, as stated
- 21 studies
- What it measured
- Glycaemic measures (HbA1c, fasting blood glucose)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis
- Studies and participants, as stated
- 24 studies (15 CBT-I/sleep hygiene; 9 sleep extension)
- What it measured
- Effects of behavioral/pharmacological sleep interventions on glucose metabolism
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis of intervention studies
- Studies and participants, as stated
- 22 studies (8 in type 2 diabetes)
- What it measured
- Prevention/early intervention of psychiatric disorders (depressive symptoms, anxiety, psychosis, suicide risk)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis (PRISMA)
- Studies and participants, as stated
- 11 studies (from 83 eligible); 7 RCTs for depression
- What it measured
- Impact of BT-I/CBT-I on depressive and fatigue symptoms
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and network meta-analysis
- Studies and participants, as stated
- 47 studies included in meta-analysis
- Heterogeneity, as stated
- Individual face-to-face CBT-I had significant effect on depressive symptoms (d=0.34, 95% CI 0.06-0.63) but not on fatigue; high heterogeneity
- What it measured
- Composite mental health (and seven specific difficulties)
- How it was read
- screened only, not extracted
- What the review says it includes
- Meta-analysis of randomized controlled trials
- Studies and participants, as stated
- 65 trials, 72 interventions, N=8608
- What it measured
- Feasibility and preliminary efficacy on sleep, blood pressure and patient-reported outcomes
- How it was read
- screened only, not extracted
- What it measured
- Difference in mean change in 24-hour ambulatory systolic blood pressure over 8 weeks
- How it was read
- screened only, not extracted
Certainty ratings the sources state (1)
- Rating, as the source states it
- Moderate
- Framework
- not named by the source
- Applies to
- Moderate-certainty evidence linked greater sleep-timing irregularity to higher depressive/anxiety symptoms, elevated BMI, insulin resistance, hypertension, cardiovascular events; low Sleep Regularity Index associated with 26-53% increased dementia risk and 20-88% higher all-cause mortality
- Stated by
- Kalkanis et al. (2025)
Every source below is shown with its study design and links to the original study. This is the audit trail.
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.