Notes
This book gives general information. It isn't medical advice, and it's no substitute for a doctor who knows your situation.
I've kept sources out of the chapters so they read easily. Here they are by chapter, with the limits I'm aware of. Where a chapter isn't listed, it rests on my own reasoning. That includes the split between the need and the method in chapter 1, the list of payments and costs in chapter 2, all of chapter 8 apart from the point about anxiety, all of chapter 10, and the six places to look in chapter 11.
A general caution applies. Research on putting off bedtime is recent. Most of it relies on people's own reports of when they meant to go to bed and when they did. Much of it comes from one group of researchers in the Netherlands. The sleep experiments are better established, but were mostly done on small groups of healthy young adults in laboratories.
Chapter 2. Control over leisure time as one of four recovery experiences is from Sonnentag and Fritz, "The Recovery Experience Questionnaire: development and validation of a measure for assessing recuperation and unwinding from work", Journal of Occupational Health Psychology 12, 2007, pages 204 to 221. The other three are detachment from work, relaxation and mastery.
Chapter 3. Kroese, Evers, Adriaanse and de Ridder, "Bedtime procrastination: a self-regulation perspective on sleep insufficiency in the general population", Journal of Health Psychology 21, 2016, pages 853 to 862. The same group introduced the idea in Kroese, De Ridder, Evers and Adriaanse, "Bedtime procrastination: introducing a new area of procrastination", Frontiers in Psychology 5, 2014, article 611. The interviews are Nauts, Kamphorst, Stut, De Ridder and Anderson, "The explanations people give for going to bed late: a qualitative study of the varieties of bedtime procrastination", Behavioral Sleep Medicine 17, 2019, pages 753 to 762. Seventeen people is a small number, chosen because they often went to bed late, and none had a diagnosed sleep disorder or worked shifts. The third pattern they found was people who delayed bed because they believed they had to be very tired before they could fall asleep. The authors suggest some of those people may have undiagnosed insomnia, which is the reason for the first caution at the front of this book.
Chapter 4. Reinecke, Hartmann and Eden, "The guilty couch potato: the role of ego depletion in reducing recovery through media use", Journal of Communication 64, 2014, pages 569 to 589. The idea of ego depletion that the study draws on has been disputed since, and I've relied only on the link the survey found between guilt and poorer recovery.
Chapter 5. The figure of seven to nine hours is from the NHS page on insomnia. Van Dongen, Maislin, Mullington and Dinges, "The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation", Sleep 26, 2003, pages 117 to 126. Palmer, Bower, Cho, Clementi, Lau, Oosterhoff and Alfano, "Sleep loss and emotion: a systematic review and meta-analysis of over 50 years of experimental research", Psychological Bulletin 150, 2024, pages 440 to 463. The findings on positive emotion and anxiety held across all kinds of sleep loss. The findings on negative emotion and on symptoms of depression were mixed.
Chapter 6. Depner, Melanson, Eckel, Snell-Bergeon, Perreault, Bergman, Higgins, Guerin, Stothard, Morton and Wright, "Ad libitum weekend recovery sleep fails to prevent metabolic dysregulation during a repeating pattern of insufficient sleep and weekend recovery sleep", Current Biology 29, 2019, pages 957 to 967. The extra weekend sleep came to about 1.1 hours in total above the participants' normal amount. Women slept less extra than men. The argument about trading poor hours for good ones is mine.
Chapter 7. Chang, Aeschbach, Duffy and Czeisler, "Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness", Proceedings of the National Academy of Sciences 112, 2015, pages 1232 to 1237. Exelmans and Van den Bulck, "Bedtime, shuteye time and electronic media: sleep displacement is a two-step process", Journal of Sleep Research 26, 2017, pages 364 to 370. The participants were aged 18 to 25 and recruited by convenience, and the figures for poor sleep were 3.3, 6.1 and 9.3 times for gaps of up to half an hour, up to an hour and over an hour. Kühnel, Syrek and Dreher, "Why don't you go to bed on time? A daily diary study on the relationships between chronotype, self-control resources and the phenomenon of bedtime procrastination", Frontiers in Psychology 9, 2018, article 77. That an engaging programme overrides sleepiness is my own suggestion. The idea that pressure to sleep builds while you're awake and falls while you sleep is from Borbély, "A two process model of sleep regulation", Human Neurobiology 1, 1982, pages 195 to 204. Applying it to a doze on the sofa is my step. The caffeine study is Drake, Roehrs, Shambroom and Roth, "Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed", Journal of Clinical Sleep Medicine 9, 2013, pages 1195 to 1200. The dose was 400 milligrams, which is a lot to take at once.
Chapter 9. Kamphorst, Nauts, De Ridder and Anderson, "Too depleted to turn in: the relevance of end-of-the-day resource depletion for reducing bedtime procrastination", Frontiers in Psychology 9, 2018, article 252. The contrary finding is in the Kühnel paper above. Moving the bedtime chores earlier is my suggestion. It follows the general principle that easier actions get done more often.
Chapter 12. That body clocks differ between people is from the Kühnel paper and the wider literature it cites. That they tend to move earlier with age is widely reported in sleep research, and I haven't cited a single study for it.
Chapter 13. Valshtein, Oettingen and Gollwitzer, "Using mental contrasting with implementation intentions to reduce bedtime procrastination: two randomised trials", Psychology and Health 35, 2020, pages 275 to 301. There were 383 students in the first trial and 221 in the second, followed for three weeks and one week. Bedtimes were reported by the students themselves. Plans in "when, then" form are from Gollwitzer and Sheeran, "Implementation intentions and goal achievement", Advances in Experimental Social Psychology 38, 2006, pages 69 to 119. The six-part method as a whole is mine and hasn't been tested as a package by anyone.
Chapter 14. The advice on insomnia and sleep apnoea follows the NHS pages on those conditions, read in September 2026. They're written for England, and services differ elsewhere.