Sleep

1. Sleeppreliminary · human dataAdded 10 September 2026

   Gut bacteria supplements may help athletes sleep better

   In a systematic review of six randomised trials with 180 exercising participants, probiotic and synbiotic supplements improved nine of twelve primary sleep outcomes, most consistently how well people felt they slept and in some cases how quickly they fell asleep.

   ⚠What it shows: Early days: a sweep of all the studies turned up just six trials totalling 180 exercising people, and the results were compared side by side rather than pooled, so better perceived sleep is a promising hint, not a verdict.Systematic review · J Int Soc Sports Nutr

   Full breakdown →Probiotics explained →Sleep Calculator →The effect of probiotic and synbiotic supplementation on sleep parameters in exercised population: a systematic review and synthesis without meta-analysis (SWiM) of randomized controlled trials. J Int Soc Sports Nutr 2026
2. Sleeppreliminary · human dataAdded 8 September 2026

   Caffeine may buy athletes performance and charge it to their sleep

   A sweep of nine randomised trials in athletes found caffeine's effects on sleep inconsistent, varying with dose, timing and habitual use. The reviewers nonetheless conclude that insomnia after ingestion is likely, and that poorer sleep could undermine the recovery athletes depend on.

   ⚠What it shows: Treat this as a caution rather than a verdict: only nine trials in athletes made the cut, and their results disagreed with each other on sleep quality, duration and awakenings. How much caffeine costs you likely depends on the dose, the timing and how accustomed to it you are.Systematic review · Clin Nutr ESPEN

   Full breakdown →Caffeine guide →Caffeine Half-Life Calculator →Does caffeine supplementation affect sleep in athletes? A systematic review of nine randomized controlled trials. Clin Nutr ESPEN 2025
3. Sleepwell supported · human dataAdded 6 September 2026

   Insomnia shows up in the blood: higher cortisol and simmering inflammation

   Adults with insomnia showed markedly elevated circulating cortisol and raised inflammatory markers including IL-6, TNF-α, CRP, IL-1β, IL-2 and IFN-γ compared with healthy sleepers, in a meta-analysis pooling 32 studies of 4578 people with insomnia and 28382 controls. Neuropeptide Y was reduced, while several other markers including BDNF showed no difference.

   ⚠What it shows: A consistent pattern but not proof of cause: results pooled from 32 studies that compared people with insomnia against healthy sleepers rather than testing anything, so it cannot say whether poor sleep drives these blood changes or something else drives both.Meta-analysis · Front Immunol

   Full breakdown →Cortisol explained →Sleep Calculator →Biomarker evidence for the pathophysiological mechanisms of insomnia: a systematic review and meta-analysis. Front Immunol 2026
4. Sleeppreliminary · human dataAdded 6 September 2026

   Yoga, Pilates and mindfulness helped new and expectant mothers sleep better

   Pooled results from 13 randomised trials in 782 perinatal women suggest mind-body therapies such as mindfulness, Pilates and yoga improve sleep quality compared with controls, though the certainty of the evidence was rated low.

   ⚠What it shows: Encouraging but shaky: results pooled from 13 trials in 782 women during and after pregnancy showed better sleep scores, yet the studies disagreed strongly with each other. The reviewers themselves rated the overall evidence as low certainty.Meta-analysis · Front Public Health

   Full breakdown →Pittsburgh Sleep Quality Index (PSQI) explained →Sleep Calculator →Effects of mind-body therapies on sleep quality in perinatal women: a systematic review and meta-analysis of randomized controlled trials. Front Public Health 2026
5. Sleeppreliminary · human dataAdded 4 September 2026

   Mindfulness helps shift nurses sleep, aromatherapy doesn't

   Pooled trial data found non-drug interventions significantly improved sleep quality in nurses working rotating shifts. Mindfulness programmes were beneficial, while aromatherapy showed no significant improvement.

   ⚠What it shows: A believable overall benefit but an untidy evidence base: results pooled from 11 trials of shift-working nurses, and the trials disagreed with each other a great deal, so the true size of the effect is uncertain. The clearest single message is that aromatherapy, one of the most popular options, did not show a significant benefit.Study · Occup Med (Lond)

   Full breakdown →Optimising Your Sleep Environment →Sleep Calculator →Non-pharmacological intervention for shift nurses' sleep: systematic review and meta-analysis. Occup Med (Lond) 2026
6. Sleeppreliminary · human dataAdded 3 September 2026

   Exercise deepens sleep in sleep apnoea, but only past 12 weeks

   In a meta-analysis of six randomised trials with 236 people with obstructive sleep apnoea, exercise programmes lasting more than 12 weeks reduced lighter stage N2 sleep and increased deep stage N3 sleep, while total sleep time, sleep efficiency and time to fall asleep did not change.

   ⚠What it shows: Encouraging but far from settled: pooled results from six trials in 236 people, and the deep sleep shift only reached significance in programmes longer than 12 weeks or once heart disease patients were set aside.Meta-analysis · J Sci Med Sport

   Full breakdown →Slow-wave sleep explained →Sleep Calculator →The effects of exercise programs on sleep architecture in obstructive sleep apnea: a meta-analysis of randomized controlled trials. J Sci Med Sport 2024
7. Sleeppreliminary · human dataAdded 3 September 2026

   A bad sleep score made people feel worse, and the score was fake

   When 63 people with insomnia were randomly given fabricated feedback about their previous night's sleep, those told their sleep efficiency had been poor reported more sleepiness and fatigue and less alert thinking by the evening than those told it had been good. Their scores on a basic reaction-time test and a measure of sleep-related attentional bias did not differ.

   ⚠What it shows: Suggestive rather than settled: one experiment in which 63 people with insomnia were randomly assigned a fake sleep score for a single day, so it says nothing about long-term tracker use or about people who sleep well. Everything that shifted was how participants rated themselves; their actual reaction-time performance barely moved.Study · J Sleep Res

   Full breakdown →Sham sleep feedback delivered via actigraphy biases daytime symptom reports in people with insomnia: Implications for insomnia disorder and wearable devices. J Sleep Res 2018
8. Sleeppreliminary · human dataAdded 2 September 2026

   GLP-1 drugs blunt sleep apnoea in people carrying extra weight

   In a pooled comparison of 15 studies covering 1,877 overweight or obese people with moderate-to-severe sleep apnoea, GLP-1 drugs cut the apnoea-hypopnoea index by 15.28 events per hour versus placebo, lowered BMI by 1.78 points and nudged up blood oxygen levels. The evidence was rated moderate certainty at best, and comparisons against exercise were mostly indirect.

   ⚠What it shows: A promising lead, not a verdict: results pooled from 15 studies with 1,877 people, none of the estimates reached high certainty, and the drug versus exercise comparisons rested largely on indirect evidence. The authors themselves call their ranking hypothesis-generating.Meta-analysis · Front Endocrinol (Lausanne)

   Full breakdown →GLP-1 explained →Efficacy of SGLT2 inhibitors, GLP-1 receptor agonists, and aerobic exercise for moderate-to-severe obstructive sleep apnea in overweight or obese patients: a network meta-analysis. Front Endocrinol (Lausanne) 2026
9. Sleeppreliminary · human dataAdded 2 September 2026

   Sleep apnoea pill cut breathing events but left fatigue unchanged

   In a 26-week trial of 646 adults with sleep apnoea who could not use CPAP, a pill combining aroxybutynin and atomoxetine cut breathing events by a model-estimated 44.1% from baseline against 17.6% on placebo, a difference of 4.0 events per hour. Fatigue scores showed no significant improvement, and 21.2% of those on the drug stopped because of side effects.

   ⚠What it shows: One large trial, and a serious one of its kind: 646 adults with mild to severe sleep apnoea who could not tolerate CPAP were assigned at random to the pill or a placebo for 26 weeks. Worth knowing that the drug's maker ran the trial and employs several of the authors, and that the average drop of 4.0 events an hour came with no significant change in fatigue.RCT · Am J Respir Crit Care Med

   Full breakdown →Apnoea–hypopnoea index explained →Aroxybutynin and atomoxetine (AD109) for obstructive sleep apnea: a randomized phase 3 trial (SynAIRgy). Am J Respir Crit Care Med 2026
10. Sleepwell supported · human dataAdded 1 September 2026

    Foot reflexology topped the list for new mothers' early sleep

    Pooling 19 randomised trials in 1,826 women across 13 drug-free approaches, foot reflexology ranked as the most effective for new mothers' sleep quality in the first 3 months after birth, while cognitive behavioural therapy for insomnia ranked best from 4 to 12 months.

    ⚠What it shows: Promising rather than final: results pooled from 19 trials in 1,826 mothers, but few of the options were ever tested against each other directly, so the rankings rest on indirect comparisons. Whether foot reflexology truly beats the rest needs head-to-head trials.Meta-analysis · J Clin Sleep Med

    Full breakdown →Pittsburgh Sleep Quality Index (PSQI) explained →Sleep Calculator →Comparative effectiveness of nonpharmacological interventions on postpartum maternal sleep quality: a systematic review and network meta-analysis. J Clin Sleep Med 2025
11. Sleepnot supported · human dataAdded 31 August 2026

    Acupressure beat no treatment for insomnia but barely beat a fake version

    A review of 40 randomised trials found acupressure, reflexology and auricular acupressure beat routine care or no treatment for insomnia, but acupressure fared only marginally better than a sham version and auricular acupressure gave equivocal results. The authors say the evidence does not allow a clear conclusion on benefit.

    ⚠What it shows: Treat the positive headlines with caution: across 40 trials, only 10 used a convincing fake version and every single study had at least one area at high risk of bias. When a therapy wins against no treatment but not against a sham, expectation may be doing much of the work.Meta-analysis · Sleep Med

    Full breakdown →Sleep Calculator →Acupressure, reflexology, and auricular acupressure for insomnia: a systematic review of randomized controlled trials. Sleep Med 2012
12. Sleeppreliminary · human dataAdded 30 August 2026

    Sleep quality tracks resilience better than sleep length

    Pooling 63 studies of healthy, non-clinical populations, sleep duration showed only a weak positive correlation with resilience (r = 0.11) while sleep quality showed a somewhat stronger one (r = 0.27); the correlation was slightly weaker in prospective studies (r = 0.18) and the authors found high publication bias for the sleep quality work.

    ⚠What it shows: Worth some weight: results pooled from 63 studies in healthy people rather than one small trial. Most measured sleep and resilience at the same moment, so neither is shown to cause the other, and the authors flagged that positive results were probably over-represented.Meta-analysis · Sleep Med Rev

    Full breakdown →Pittsburgh Sleep Quality Index (PSQI) explained →Sleep Calculator →A systematic review and meta-analysis to assess the relationship between sleep duration/quality, mental toughness and resilience amongst healthy individuals. Sleep Med Rev 2022
13. Sleeppreliminary · human dataAdded 30 August 2026

    Yoga Nidra shortened the time to fall asleep across six small trials

    A review of six randomised trials with 244 participants found most reported improvements in sleep onset latency, total sleep time and sleep efficiency with Yoga Nidra, a guided meditative practice, compared with controls including cognitive behavioural therapy for insomnia, progressive muscle relaxation and music-based relaxation. Most trials carried moderate to high risk of bias and adverse events were poorly reported.

    ⚠What it shows: Promising rather than proven: a sweep of the literature turned up only six trials with 244 people between them, and most were rated at moderate to high risk of bias because participants knew what they were getting and results were reported incompletely. Protocols and outcome measures also varied a lot, and safety data was barely reported.Systematic review · J Integr Complement Med

    Full breakdown →Pittsburgh Sleep Quality Index (PSQI) explained →Sleep Calculator →Efficacy of Yoga Nidra in Managing Sleep Disorders: A Systematic Review of Randomized Controlled Trials. J Integr Complement Med 2026
14. Sleeppreliminary · human dataAdded 30 August 2026

    Sleep apnoea dulls sex life in both sexes; only men have treatment trials

    A review of 21 studies found sexual function was affected similarly in women and men with obstructive sleep apnoea, but effective interventions were reported only for men. Continuous positive airway pressure improved erectile and orgasmic function as well as excessive daytime sleepiness, although sildenafil was superior to CPAP for erectile dysfunction.

    ⚠What it shows: Treat as an evidence gap rather than a verdict: a sweep of 21 studies, of which only 6 included women and none of those tested a treatment by assigning people at random. The authors say firm generalisations cannot be made, so the women's side of this rests on very thin ground.Systematic review · Int J Clin Pract

    Full breakdown →Determinants of sexual dysfunction and interventions for patients with obstructive sleep apnoea: a systematic review. Int J Clin Pract 2016
15. Sleepwell supported · human dataAdded 29 August 2026

    Cut sleep and insulin sensitivity drops; fragment it and nothing happens

    Restricting sleep reduced insulin sensitivity in a meta-analysis of randomised trials, and both shifting sleep timing against the body clock and suppressing deep sleep also impaired it, while fragmented sleep and disturbed REM sleep had no measurable effect.

    ⚠What it shows: Strong for a short-term effect: results pooled from 21 trials where sleep was deliberately cut show insulin sensitivity dropping on several different measures. These were brief laboratory-style manipulations, so they cannot say how years of habitually short sleep play out.Meta-analysis · Sleep Med Rev

    Full breakdown →Insulin sensitivity explained →Sleep Calculator →Effects of sleep manipulation on markers of insulin sensitivity: A systematic review and meta-analysis of randomized controlled trials. Sleep Med Rev 2022
16. Sleeppreliminary · human dataAdded 25 August 2026

    Both short and long sleepers show older-looking organs

    Across 23 biological ageing clocks built from imaging, blood proteins and metabolites in UK Biobank participants aged 37 to 84, self-reported sleep duration showed a U-shaped relationship with biological age gaps, with the lowest gaps falling between 6.4 and 7.8 hours depending on organ and sex. Sleeping under 6 hours or over 8 hours, compared with 6 to 8 hours, was associated with higher risk of systemic diseases including depression and diabetes, and with all-cause mortality.

    ⚠What it shows: Strong data, soft measurement: a very large sample with 23 different ageing markers, but sleep was self-reported and people were followed rather than assigned sleep lengths, so illness driving short or long sleep cannot be ruled out.Study · Nature

    Full breakdown →Biological age explained →Phenotypic Age Calculator →Sleep chart of biological ageing clocks in middle and late life. Nature 2026
17. Sleeppreliminary · human dataAdded 23 August 2026

    Evening workouts do not wreck your sleep, with one caveat for hard sessions

    Pooling 16 randomised trials, morning exercise showed no clear overall advantage over evening exercise for most sleep outcomes, though evening sessions were linked with more time awake after falling asleep, especially at higher intensities.

    ⚠What it shows: A solid verdict from results pooled across 16 trials where people were assigned at random: the review backs exercising at whichever time you can stick to. The one downside found for evening sessions leaned on smaller studies, so treat that part as tentative.Review · Sleep Med Rev

    Full breakdown →Meta-analysis explained →Sleep Calculator →Effects of morning versus evening exercise on sleep: a systematic review of comparative studies with a meta-analysis of randomized controlled trials. Sleep Med Rev 2026
18. Sleepwell supported · human dataAdded 23 August 2026

    Insomnia therapy through a screen works, and keeps working a year on

    Digital cognitive behavioural therapy for insomnia reduced insomnia severity scores by 5.00 points versus control across 33 randomised trials, and the improvement was still present at 1-year follow-up. Face-to-face therapy did somewhat better, but within the margin regarded as comparable.

    ⚠What it shows: Strong evidence: results pooled from 33 trials in adults with insomnia, and the benefit persisted a full year. The studies disagreed with each other on the size of the effect, and most compared the therapy against waiting lists or usual care rather than a convincing placebo.Meta-analysis · Sleep Med

    Full breakdown →Pittsburgh Sleep Quality Index (PSQI) explained →Sleep Calculator →Efficacy of digital cognitive behavioural therapy for insomnia: a meta-analysis of randomised controlled trials. Sleep Med 2020
19. Sleepwell supported · human dataAdded 23 August 2026

    Massage and exercise top the list for new mothers' sleep

    Non-drug approaches improved new mothers' self-reported sleep in pooled trial data, with massage and exercise showing the largest effects. Infants' night-time sleep also improved slightly, but maternal depression did not shift.

    ⚠What it shows: Reasonably solid but resting on self-report: results pooled from 15 studies of new mothers, with sleep judged by the mothers themselves rather than measured objectively. Whether the gains last, or show up on sleep recordings, is still unknown.Meta-analysis · Sleep Med Rev

    Full breakdown →Optimising Your Sleep Environment →Sleep Calculator →Non-pharmacological interventions for improving postpartum maternal sleep: A systematic review and meta-analysis. Sleep Med Rev 2018
20. Sleeppreliminary · human dataAdded 23 August 2026

    Talking therapy tops the drug-free rankings for poor sleep after 60

    Across 34 randomised trials in 3078 adults aged 60 and over, cognitive behavioural therapy for insomnia, especially when combined with positive mood strategies, ranked as the most effective of 21 drug-free approaches to improving sleep quality.

    ⚠What it shows: Useful rankings, low certainty: results pooled from 34 trials in 3078 older adults compared 21 approaches indirectly, and the authors rate the overall evidence as low certainty. Which option came out best also shifted with how bad sleep was to begin with.Meta-analysis · BMC Med

    Full breakdown →Sleep Calculator →Effects of non-pharmacological interventions on sleep quality in older adults: a systematic review and network meta-analysis of randomized controlled trials. BMC Med 2026
21. Sleepwell supported · human dataAdded 22 August 2026

    Muscle relaxation improved sleep, and extra sessions added nothing

    Progressive muscle relaxation improved subjective sleep quality in adults across 14 trials involving 957 people, with clear benefits in adults under 55 but uncertain effects in those aged 55 and older, and doing more sessions was not linked to better sleep.

    ⚠What it shows: Encouraging but not airtight: pooled results from 14 trials in 957 people showed better sleep, but the studies disagreed with each other a lot and sleep was rated by questionnaire rather than measured by monitors, so the true size of the benefit is uncertain.Meta-analysis · Front Public Health

    Full breakdown →Sleep Calculator →The effects of progressive muscle relaxation on sleep quality in adults: a systematic review and meta-analysis of randomized controlled trials. Front Public Health 2026
22. Sleeppreliminary · human dataAdded 21 August 2026

    Pressing the right points may help older adults sleep, even self-applied

    Acupressure improved sleep quality in older adults compared with controls across 11 randomised trials totalling 722 people. The benefit held even when participants were trained to apply the pressure themselves, though it looked smaller.

    ⚠What it shows: Promising rather than proven: results pooled from 11 small trials in 722 older people all pointed the same general way, but the studies disagreed with each other a great deal, so the size of the benefit is shaky.Meta-analysis · Explore (NY)

    Full breakdown →Sleep Calculator →The effect of acupressure on sleep quality of older people: A systematic review and meta-analysis of randomized controlled trials. Explore (NY) 2022
23. Sleepwell supported · human dataAdded 21 August 2026

    Insomnia therapy through a screen works nearly as well as in person

    Digital psychosocial treatments for insomnia substantially reduced insomnia severity and improved sleep quality compared with no treatment across 37 randomised trials with 13,227 adults. They showed no significant difference from in-person treatment on insomnia severity, though face-to-face care kept an advantage on sleep quality, and guidance from trained human therapists improved results.

    ⚠What it shows: Strong evidence: results pooled from 37 trials covering 13,227 adults, with no sign that missing negative studies skewed the picture. The one clear gap is that face-to-face treatment still beat digital delivery on sleep quality, and programmes without a real therapist behind them did less well.Meta-analysis · J Med Internet Res

    Full breakdown →Optimising Your Sleep Environment →Sleep Calculator →eHealth-Based Psychosocial Interventions for Adults With Insomnia: Systematic Review and Meta-analysis of Randomized Controlled Trials. J Med Internet Res 2023
24. Sleeppreliminary · human dataAdded 20 August 2026

    Qigong improved sleep, though placebo may share the credit

    Health qigong improved self-reported sleep quality in pooled randomised trials involving 1,147 adults with and without health conditions, though the effect shrank to small once one outlier study was removed.

    ⚠What it shows: Promising rather than proven: results pooled from 13 trials with 1,147 adults, but the trials disagreed sharply and the benefit turned small after removing one outlier. Half the studies compared qigong with doing nothing, so expectation effects were not ruled out.Meta-analysis · Complement Ther Med

    Full breakdown →Breathwork for Recovery and Stress →Sleep Calculator →Effects of health qigong on sleep quality: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med 2022

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