Tuning daytime and evening light did not improve older adults' sleep
In a 12-person crossover trial, blue-enriched daytime light with reduced evening blue did not cut time spent awake at night, though it nudged a brainwave marker of sleep.
Light alone barely moved young adults' clocks; a combined package did
Two small pilot studies in 18-to-25-year-olds found morning bright light on its own shifted circadian timing little, while adding a timed schedule and evening blue-blockers advanced it about 35 minutes.
What mouth taping is, and the one thing to rule out before trying it
It is a strip of tape over the lips at night, meant to force nose breathing. The idea is simple; the safety caveat is the part that matters most.
Most snoring is harmless. What quiets it depends on why you snore
The remedies that work are the ones matched to the cause — nose, mouth, tongue or palate. Here is what the trials support, and the sign that means see a doctor first.
Alcohol disrupts REM sleep from about two drinks. It only speeds sleep onset at five.
A meta-analysis of 27 studies found a dose-response pattern that runs against the nightcap logic: the sedative effect needs a high dose, and the REM disruption starts at a low one.
A new magnesium trial found real cognitive gains and a sleep signal too soft to call a win
Participants on Magtein scored better on memory and reaction-time tests after six weeks. On sleep — the reason most people buy it — an Oura Ring found no measurable difference at all.
An AI read one night of sleep and forecast 130 diseases. Read the fine print.
Stanford's SleepFM, published in Nature Medicine in January 2026, is the most consequential sleep paper of the year. Its own limitations section explains why it is not yet a clinical test.
Nasal strips help some snorers breathe easier. The research is honest about the limit.
External nasal strips have real, repeatable evidence behind mild snoring relief. They have never been shown to treat sleep apnea, and the two problems are not the same problem.
Mouth taping is everywhere on social media. Here is what the evidence actually shows.
The practice has real theory behind it and a genuine safety warning attached to it. The studies are small, mostly low quality, and say less than either side of the debate claims.
Time of day changes what you can lift, not how much you gain from training
A review screening 14,125 articles found evidence neither for nor against morning or evening training — only that testing and training at the same hour helps. Evening sessions may cost some sleep continuity.
Waking in the night is the norm. Struggling to get back to sleep is not.
About a third of adults on two continents wake at least three nights a week. The 7.7% who cannot resume sleep carry almost all of the daytime damage — and the cause is often not what the sleeper thinks.
Obesity and sleep disorders track with worse semen. Alcohol mostly does not.
An umbrella review graded 249 effect sizes across 67 risk factors for male infertility. More than half were rated very low certainty — and the review contradicts its own table on one of them.
Weekend lie-ins did not undo a week of short nights in two laboratory studies
In-lab trials that restricted sleep on weekdays and allowed recovery at the weekend found insulin sensitivity and glucose tolerance still worsened. Population surveys point the other way, and the designs explain why.
Blue-light glasses: what 17 randomised trials could and could not show
A Cochrane review found they may not reduce eye strain and could not determine whether they help sleep. A separate meta-analysis found small effects. Neither found the evidence anyone assumes exists.
Prenatal PFAS and two child outcomes: sleep scores and bone density
A 2,836-pair analysis of the ECHO cohort found one of four compounds associated with parent-reported sleep problems. A Shanghai study of bone density found opposite directions in girls and boys.
Evening screens shift bedtimes. The blue light is the smaller part of it.
A laboratory trial found a light-emitting e-reader really does suppress melatonin and delay the body clock. Two 2026 field studies found the day-to-day effect runs almost entirely through when people go to bed.
One insomnia treatment carries a strong recommendation. No sleeping pill does.
Two American guideline bodies grade cognitive behavioural therapy for insomnia as a strong recommendation. Every drug in the sleep-medicine guideline — the ones it endorses and the ones it rejects — came out weak.
Five cohorts, 44 sleep measurements, no association with dementia risk
A consortium reduced overnight sleep studies to nine composites. Two tracked with better cognition. None tracked with whether a person later developed dementia.
Short naps sharpened alertness. Long habitual naps tracked with worse outcomes.
A meta-analysis of 44 cohorts covering 1,864,274 people found the risk signal attached to naps of 30 minutes or more. Below that threshold, no significant risk appeared.
Sleep medicine's own guideline suggests clinicians not use melatonin for insomnia
The pooled effect is about seven minutes off the time it takes to fall asleep. The American Academy of Sleep Medicine recommends against it — on evidence it grades as weak in both directions.
The sleep guideline says seven or more hours. It has never said eight.
The number most people quote is not the number the American Academy of Sleep Medicine and Sleep Research Society agreed on. Their recommendation is a floor, set by expert vote rather than by trial.
For jet lag, the evidence on melatonin is unusually strong. Timing is the catch.
A Cochrane review found melatonin reduced jet lag in nine of ten trials. Sleep medicine's own guideline rates it a first-tier option for jet lag disorder. Take it at the wrong hour and it can make things worse.
Elite karate athletes lost the most performance at 5pm in week four of Ramadan
A twelve-athlete study tested morning, late-afternoon and late-evening sessions across the fasting month — and found the deficit was specific to time of day, not spread evenly across it.
Sleep got worse during Ramadan and mood mostly didn't — in a cohort of 30 Saudi women
Stress peaked during the fasting month and fell afterwards, but depression and anxiety stayed flat. The consistent finding across every phase was that sleep quality tracked mental health.
The nitric oxide argument for nasal breathing, checked against the physiology
The sinuses really do produce nitric oxide at concentrations far above the lower airway. Whether routing more of it through your lungs at night does anything measurable is a separate, unanswered question.
Sleep questionnaires are good at ruling out, and poor at ruling in
The best-validated sleep apnea screener works by being wrong in a specific direction. A 47-study meta-analysis of 26,547 people shows what a questionnaire can and cannot conclude about you.
Who misuses sedatives to sleep? A US survey finds two different populations, not one
An analysis of nearly 139,000 Americans finds sedative misuse for sleep clusters among both the socially advantaged and the chronically unwell — pointing to two distinct drivers behind the same behavior.
College athletes gained 33 minutes of sleep. Mental health talk has not moved
The NCAA's fifth GOALS study surveyed 20,887 athletes. Sleep is up across almost every sport. Comfort talking to coaches about mental health has barely moved in a decade.
Blood cells enter the brain during sleep to haul away lipids, a fly study finds
The clearance story about sleep has been brain-centric. A Nature paper reports that in Drosophila, immune cells from the circulation do part of the job — and that blocking them shortens sleep.
Mouth breathing at night: is it causing the problem or signalling it?
Breathing through the mouth in sleep tracks closely with sleep apnea severity. The direction of the arrow is the part the research has not settled, and it changes what any intervention can claim.
Three new studies on step counts agree on one thing: the number alone is not enough
A UK Biobank analysis finds high step counts do not offset short sleep. A US cohort finds one-minute bursts matter. And in older adults, most step-count differences vanish after adjusting for age and sex.
Sleeping more helps athletes. The evidence for it is thinner than its fame.
The famous Stanford basketball study had eleven players and no control group. Fifteen years on, sleep extension is still the best-supported sleep intervention in sport, and still barely studied.
Weekend lie-ins tracked with fewer depressive symptoms in a national youth survey
Among 16-to-24-year-olds in NHANES, those who slept longer on weekends had 41% lower odds of daily depressive symptoms. The survey measured both at the same moment, which limits what can be concluded.
A small insomnia trial asked when in the day a sleeping pill helps — and when it hurts
Standard questionnaires found no daytime difference between suvorexant and placebo. Four-times-daily smartphone prompts found fatigue worse in the morning and better later. The trial had 40 people.
Yoga is recommended for sleep. Against plain stretching, it did nothing extra.
A 240-woman randomised trial compared three months of hatha yoga with a time-matched conditioning programme. On every sleep measure, the two groups moved together.
Two non-hormonal menopause drugs look similar on hot flushes, differ on sleep
An industry-standard indirect comparison of fezolinetant and elinzanetant found comparable reductions in vasomotor symptoms. Elinzanetant improved sleep disturbance more, without a difference in overall quality of life.
Experts rated chatbot sleep advice for athletes as valid. Jet lag advice mostly failed
Twenty experts scored three language models on ten common questions. One model cleared the content validity bar on both topics; another scored zero on jet lag.
Sleep hygiene advice works better as a companion than as a treatment
Forty-two trials show sleep-hygiene education helps a little and helps less than the alternatives. The sleep-medicine guideline suggests clinicians not use it on its own.
A tuned LLM outscored experts on sleep and fitness exams. Then came the hard part
Google's PH-LLM beat sampled human experts on multiple-choice tests but only matched them on real cases. A new reporting checklist published the same month explains why such claims are hard to compare.