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Sources
Updated October 3, 2026
Facts and numbers on this site trace to the publications below. Government works are public domain; journal findings are cited by DOI; Wikipedia text is adapted under CC BY-SA 4.0; Mayo Clinic figures are used as numbers only.
| Source | Publisher | What we take from it |
|---|---|---|
| Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke (NIH) | sleep stages; a full cycle lasts roughly 90 minutes; cycles repeat 4-6 times per night; public domain (US government work) |
| How Sleep Works - Sleep Phases and Stages | National Heart, Lung, and Blood Institute (NIH) | stage sequence and the 90-minute cycle estimate; public domain |
| Sleep cycles - Sleep Education | American Academy of Sleep Medicine | cycle length varies 70-120 minutes between people and across the night; first cycle is usually shortest; facts cited, no text copied |
| Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the AASM and Sleep Research Society | Sleep 38(6):843-844, 2015 | adults should sleep 7 or more hours per night on a regular basis |
| National Sleep Foundation's sleep time duration recommendations: methodology and results summary | Sleep Health 1(1):40-43, 2015 (Hirshkowitz M. et al.) | the nine age groups, recommended ranges, and 'may be appropriate' ranges |
| Recommended Amount of Sleep for Pediatric Populations: A Consensus Statement of the American Academy of Sleep Medicine | J Clin Sleep Med 12(6):785-786, 2016 (Paruthi S. et al.) | AASM pediatric ranges (4-12 months 12-16 h; 1-2 y 11-14 h; 3-5 y 10-13 h; 6-12 y 9-12 h; 13-18 y 8-10 h) |
| Recommended Amount of Sleep for a Healthy Adult (AASM and Sleep Research Society consensus) | Sleep 38(6):843-844, 2015 (Watson N.F. et al.) | adults 18-60: 7 or more hours per night |
| How Much Sleep Do I Need? | Centers for Disease Control and Prevention (CDC) | summary table by age group; public domain (US government work) |
| A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative? | Sleep 29(6):831-840, 2006 (Brooks A., Lack L.) | 5/10/20/30-minute nap comparison; 10 minutes best immediate benefit; 30 minutes shows sleep inertia |
| Alertness Management: Strategic Naps in Operational Settings | NASA Technical Memorandum 108839 (Rosekind M.R. et al.), 1995; also J Sleep Res 4(S2):62-66 | 26-minute average nap; 34% performance and 54% alertness improvement; public domain (NASA) |
| Sleep inertia | Sleep Medicine Reviews 4(4):341-353, 2000 (Tassi P., Muzet A.) | sleep inertia duration and link to waking from slow-wave sleep |
| Brain Basics: Understanding Sleep | NINDS (NIH) | 90-minute cycle; public domain |
| Caffeine content for coffee, tea, soda and more | Mayo Clinic | typical mg per serving (facts cited, no text copied); Mayo cites USDA FoodData Central |
| Spilling the Beans: How Much Caffeine is Too Much? | U.S. Food and Drug Administration | 400 mg/day for healthy adults; half-life 4-6 hours; typical ranges for coffee, cola, energy drinks, decaf; public domain |
| FoodData Central | U.S. Department of Agriculture | caffeine per 100 g for beverages and chocolate; public domain |
| Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed | J Clin Sleep Med 9(11):1195-1200, 2013 (Drake C. et al.) | 400 mg taken 6 h before bed reduced total sleep time by more than 1 hour (objective measure) |
| Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations | National Academies Press, 2001 | caffeine half-life about 5 h in healthy adults, range roughly 1.5-9.5 h |
| Colors of noise | Wikipedia (CC BY-SA 4.0) | spectral definitions of white (flat), pink (-3 dB/octave) and brown/red (-6 dB/octave) noise; credit + link required |
| Broadband Sound Administration Improves Sleep Onset Latency in Healthy Subjects in a Model of Sleep Onset Insomnia | Frontiers in Neurology 8:718, 2017 (Messineo L. et al.) | white-noise-like broadband sound reduced time to fall asleep by about 38% in a small lab study (n=18) |
| Acoustic Enhancement of Sleep Slow Oscillations and Concomitant Memory Improvement in Older Adults | Frontiers in Human Neuroscience 11:109, 2017 (Papalambros N.A. et al.) | timed pink-noise pulses increased slow-wave activity in older adults (n=13); not the same as playing pink noise all night |
| Noise as a sleep aid: A systematic review | Sleep Medicine Reviews 55:101385, 2021 (Riedy S.M. et al.) | evidence for continuous noise as a sleep aid is limited and of low quality; some studies show benefit, some show disruption |
Not used
Editorial tables from commercial sleep sites (used only to double-check figures, never cited), caffeine databases without a reuse licence, forum posts, and any AI-generated image.
Corrections log
2026-10-03: first publication, snapshot of all data files.