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Rules for better rest go back to 1864, when Italian physician Paolo Mantegazza wrote about the hygiene of sleep, and Nathaniel Kleitman began studying circadian rhythms in the 1930s. The modern checklist was codified in the late 1970s by psychologist Peter Hauri for mild to moderate insomnia, and it rests on four pillars: schedule, activities, substances and environment. The episode walks through the biology: shifting wake times on weekends causes social jet lag, long late naps drain the adenosine that builds sleep pressure, so naps should be 20 to 30 minutes and before 2 p.m., and late intense exercise raises body temperature when it needs to fall. If sleep does not come within 20 minutes, the advice is to get up and go to a dim room. Alcohol speeds sleep onset through GABA but brings a rebound of micro-awakenings and suppressed REM sleep.

In 2021 the American Academy of Sleep Medicine concluded that sleep hygiene should not be used as a standalone therapy for chronic insomnia, because evidence that it cures the condition was weak. Inadequate sleep hygiene had already been dropped as a diagnosis from the International Classification of Sleep Disorders in 2014. The gold standard instead is cognitive behavioral therapy for insomnia, including sleep restriction, which limits time in bed to build sleep pressure. The episode then turns to people who cannot follow the rules: shift workers with inverted melatonin cycles, patients whose asthma and allergy drugs act as stimulants, and lower-income households facing noise, light pollution and unsafe neighborhoods that keep the stress response switched on. Proposed fixes include stable scheduling rules, green space, community safety and home testing with wearables.

• Patients often show sleep state misperception, believing they lay awake when brain readings show light sleep.
• Actigraphy uses a wrist-worn piezoelectric accelerometer to track sleep and wake patterns at home over days.
• The AI-driven SleepEval system draws on a bank of 1,543 possible questions mapped to sleep disorder classifications.
• A 2015 systematic review found medium-firm, custom-inflated mattresses reduced musculoskeletal pain.
• Chronic hypervigilance in unsafe neighborhoods keeps cortisol elevated, which works against deep slow-wave sleep.