Sleep duration
Sleep problems worsened years before a psychiatric diagnosis in working-age Swedes and partly eased after it
Karolinska Institutet and Stockholm University researchers matched eight years of sleep surveys from about 25,000 Swedes to health registers. Mental fatigue had the strongest link to a later diagnosis, yet fewer than 3 in 100 got one.
Sep 14, 2026
One all-nighter hit driving harder than four short nights
A trial in SLEEP put the same 20 men through a night with no sleep, four nights of two hours less, and normal sleep, then a simulated dawn commute. The all-nighter degraded lane control within minutes. The gradual loss barely showed.
Aug 9, 2026
Insomnia tracked death risk only when sleep was measured
In the Wisconsin Sleep Cohort, 767 adults were followed for a median of eight years. Insomnia with under six hours on an overnight recording carried 2.6 times the risk of dying. Insomnia with self-reported short sleep carried none.
Aug 8, 2026
Short and long sleep both tracked with Alzheimer changes
Using brain scans from 38,816 UK Biobank participants, researchers found a U-shaped pattern: five to six hours and nine to ten hours both lined up with more Alzheimer-like shrinkage and worse test scores.
Aug 4, 2026
Longer sleep steadied next-day blood sugar in teenagers
A SLEEP study paired wrist trackers with continuous glucose monitors across 2,245 days in 206 Danish 18-year-olds and found sleep and glucose pushing on each other in both directions.
Jul 29, 2026
Getting a phone at 13 cost sleep, not mood
A JAMA Pediatrics study followed 1,959 teenagers from age 13 to 14 and found that getting a smartphone tracked with less sleep, while depression and obesity tracked with how much it was used.
Jul 28, 2026
Sleep of 7 hours tracked 30% lower death risk by watch and 14% by self-report
Everyone is told to get seven hours, advice built from questionnaires. Following 76,811 UK adults who both wore a tracker and estimated their own sleep, the healthiest amount and the size of the benefit each shifted with the method.
Jul 25, 2026
Bedtime procrastination cost students 1.4 hours of sleep
Researchers wired a residential college with Bluetooth beacons and sleep watches for two weeks and found students who delayed bedtime to socialize slept 1.4 hours less and felt worse the next day.
Jul 25, 2026
Losing 80 minutes of sleep a night led to weight gain
In a Columbia University trial, 95 adults who cut their nightly sleep by about 80 minutes for six weeks gained roughly a pound, and the gain came from moving less rather than eating more.
Jul 22, 2026