Sleep

Topics

• Bedroom temperature

  Real-world and laboratory studies consistently find that warmer nights and hot bedrooms are linked with shorter, less efficient sleep, with older adults among the most affected; one home-monitoring study of older adults found sleep was most efficient between about 20 and 25 °C. Children who sleep in rooms that are too hot or too cold also show poorer sleep, and paediatric guidance lists avoiding overheating as part of a safe infant sleep environment. No claim reaches moderate or high certainty because the evidence is mostly observational or from small laboratory studies, and the systematic review did not pool results.

  • Sleep

  6 claims

• CBT-I for insomnia

  Cognitive behavioural therapy for insomnia (CBT-I) is a structured, multicomponent programme combining cognitive work around sleep with behavioural methods such as stimulus control and sleep restriction. In randomised trials of adults living with long-term insomnia symptoms it shortened time to fall asleep and time awake at night, including when delivered over the internet and alongside other health conditions, and major clinical guidelines recommend it as the first approach. Sleep restriction can bring temporary daytime sleepiness in the first weeks.

  • Mind
  • Sleep

  5 claims

• Light exposure and circadian rhythm

  Light is the main signal that sets the body clock: in adults, evening and night light reduces the evening rise in melatonin and can increase alertness before bed, while brighter daytime light is associated with better sleep, mood and earlier body-clock timing. Large UK cohort studies link bright days and dark nights with lower all-cause mortality, and a meta-analysis found bright light sessions improved sleep problems with small to medium effects. Most of the population-level evidence is observational, so only the melatonin effect reaches moderate certainty.

  • Longevity
  • Mind
  • Sleep

  4 claims

• Sleep duration and regularity

  Expert panels describe 7 to 9 hours a night as appropriate for healthy adults (7 to 8 hours for older adults). In population studies both habitually short and habitually long sleep are associated with higher mortality, and short sleep with obesity and type 2 diabetes, but this evidence is observational. More regular sleep timing is associated with better health and lower mortality in cohorts, and experiments show that acute sleep loss impairs attention.

  • Longevity
  • Mind
  • Sleep

  5 claims