Things about sleep.
Do we sleep enough?
The photogenic researcher who keeps on making pronouncements about the pathologies of modern work schedules, and whose name I can never remember is Till Roenneberg. He is attached to, e.g. the EUCLOCK project, and the MPG and LMU etc. I’m not convinced, BTW, by the Munich Chronotype Questionaire due to him and Martha Merrow; the questions make almost no sense for my own personal routine, so I wonder who else they cover poorly? However, the strident lifestyle advice that these folks give out rests on more data than that particular survey.
If you take one thing away from this entire essay, remember this: as long as you feel good, sleeping anywhere between 5 and 8 hours a night seems basically fine for your health (see Section 1), regardless of whatever Big Sleep wants you to believe.
All of the evidence we have about sleep and long-term health is in the form of those essentially meaningless correlational studies, but if you’re going to use bad science to guide your sleep habits, at least use accurate bad science.
Why do we sleep?
We have known for quite awhile now that light is the most powerful cue for shifting the phase or resetting the time of the circadian clock. We also know that melatonin is present at low levels during the day, begins being released a few hours before bedtime and peaks in the middle of the night. Past studies have shown that light suppresses melatonin, such that light in the early evening causes a circadian delay, or resets the clock to a later schedule; and light in the early morning causes a circadian advancement, or resets the clock to an earlier schedule. … we found that humans display a peak sensitivity to light in the blue wavelength region of the spectrum. Rods and cones … could not account for this differential regulation of melatonin production, so we postulated another type of photoreceptor was responsible for mediating such physiological responses. These wavelength-sensitive photoreceptors were identified soon after and are known as melanopsin-containing ganglion cells
The 2005 meta-analysis Brzezinski et al concluded that, over all (mostly healthy) adult participants, melatonin improved on placebo to the extent that it [statistically-]significantly reduced sleep onset latency by 4.0 min (95% CI 2.5-5.4) [The normal limits for latency to sleep are considered to be 15-20 min.]; increased sleep efficiency by 2.2% (95% CI 0.2-4.2) [The normal sleep efficiency is about 90-95%.], and increased total sleep duration by 12.8 min (95% CI 2.9-22.8). … One might object that they do not wish to tamper with their natural sleep, even if melatonin is a normally-secreted hormone. Sad to say, I would point out to such readers that they are already profoundly tampering with their natural sleep cycle, and indeed, all of Western civilization is tampering with it; most of my readers do not even sleep multiple times during the day, as Nature intends and as humans have usually slept through history …
So if you want to go to sleep (and wake up) earlier, you want to take melatonin early in the day. How early? Van Geijlswijk et al sums up the research as saying it is most effective “5 hours prior to both the traditionally determined [dim light melatonin onset] (circadian time 9)”. If you don’t know your own melatonin cycle, your best bet is to take it 9 hours after you wake up (which is presumably about seven hours before you go to sleep).
Belenky, Gregory, Nancy J. Wesensten, David R. Thorne, Maria L. Thomas, Helen C. Sing, Daniel P. Redmond, Michael B. Russo, and Thomas J. Balkin. 2003. “Patterns of Performance Degradation and Restoration During Sleep Restriction and Subsequent Recovery: A Sleep Dose-Response Study.” Journal of Sleep Research 12 (1): 1–12. https://doi.org/10.1046/j.1365-2869.2003.00337.x.
Chee, Michael W. L., Jiat Chow Tan, Hui Zheng, Sarayu Parimal, Daniel H. Weissman, Vitali Zagorodnov, and David F. Dinges. 2008. “Lapsing During Sleep Deprivation Is Associated with Distributed Changes in Brain Activation.” The Journal of Neuroscience 28 (21): 5519–28. https://doi.org/10.1523/JNEUROSCI.0733-08.2008.
Dinges, David F. 1995. “An Overview of Sleepiness and Accidents.” Journal of Sleep Research 4 (December): 4–14. https://doi.org/10.1111/j.1365-2869.1995.tb00220.x.
Durmer, Jeffrey S., and David F. Dinges. 2005. “Neurocognitive Consequences of Sleep Deprivation.” In SEMINARS IN NEUROLOGY. Vol. 25. http://faculty.vet.upenn.edu/uep/assets/user-content/documents/DurmerandDinges--NeurocognitiveConsequences--SEM.NEUROL.2005.pdf.
Foster, Russell G., and Katharina Wulff. 2005. “The Rhythm of Rest and Excess.” Nature Reviews Neuroscience 6 (5): 407–14. https://doi.org/10.1038/nrn1670.
Fultz, Nina E., Giorgio Bonmassar, Kawin Setsompop, Robert A. Stickgold, Bruce R. Rosen, Jonathan R. Polimeni, and Laura D. Lewis. 2019. “Coupled Electrophysiological, Hemodynamic, and Cerebrospinal Fluid Oscillations in Human Sleep.” Science 366 (6465): 628–31. https://doi.org/10.1126/science.aax5440.
Gomes, Ana Allen, José Tavares, and Maria Helena P. de Azevedo. 2011. “Sleep and Academic Performance in Undergraduates: A Multi-Measure, Multi-Predictor Approach.” Chronobiology International 28 (9): 786–801. https://doi.org/10.3109/07420528.2011.606518.
Hafner, Marco, Martin Stepanek, Jirka Taylor, Wendy Troxel, and Christian Stolk. 2016. “Why Sleep Matters – the Economic Costs of Insufficient Sleep: A Cross-Country Comparative Analysis.” RAND Corporation. https://doi.org/10.7249/RR1791.
Harrison, Y., and J. A. Horne. 2000. “The Impact of Sleep Deprivation on Decision Making: A Review.” Journal of Experimental Psychology. Applied 6 (3): 236–49. http://postcog.ucd.ie/files/Hrrison%20and%20horne.pdf.
Heugten-van der Kloet, Dalena van, Timo Giesbrecht, and Harald Merckelbach. 2015. “Sleep Loss Increases Dissociation and Affects Memory for Emotional Stimuli.” Journal of Behavior Therapy and Experimental Psychiatry 47 (June): 9–17. https://doi.org/10.1016/j.jbtep.2014.11.002.
Killgore, William D. S., Ellen T. Kahn-Greene, Erica L. Lipizzi, Rachel A. Newman, Gary H. Kamimori, and Thomas J. Balkin. 2008. “Sleep Deprivation Reduces Perceived Emotional Intelligence and Constructive Thinking Skills.” Sleep Medicine 9 (5): 517–26. https://doi.org/10.1016/j.sleep.2007.07.003.
Levandovski, Rosa, Giovana Dantas, Luciana Carvalho Fernandes, Wolnei Caumo, Iraci Torres, Till Roenneberg, Maria Paz Loayza Hidalgo, and Karla Viviani Allebrandt. 2011. “Depression Scores Associate with Chronotype and Social Jetlag in a Rural Population.” Chronobiology International 28 (9): 771–78. https://doi.org/10.3109/07420528.2011.602445.
Lockley, Steven W., John W. Cronin, Erin E. Evans, Brian E. Cade, Clark J. Lee, Christopher P. Landrigan, Jeffrey M. Rothschild, et al. 2004. “Effect of Reducing Interns’ Weekly Work Hours on Sleep and Attentional Failures.” New England Journal of Medicine 351 (18): 1829–37. https://doi.org/10.1056/NEJMoa041404.
Lucassen, Eliane A., Xiongce Zhao, Kristina I. Rother, Megan S. Mattingly, Amber B. Courville, Lilian de Jonge, Gyorgy Csako, and Giovanni Cizza. 2013. “Evening Chronotype Is Associated with Changes in Eating Behavior, More Sleep Apnea, and Increased Stress Hormones in Short Sleeping Obese Individuals.” PLoS ONE 8 (3): e56519. https://doi.org/10.1371/journal.pone.0056519.
Mohtashami, Fariba, Allison Thiele, Erwin Karreman, and John Thiel. 2014. “Comparing Technical Dexterity of Sleep-Deprived Versus Intoxicated Surgeons.” JSLS: Journal of the Society of Laparoendoscopic Surgeons / Society of Laparoendoscopic Surgeons 18 (4). https://doi.org/10.4293/JSLS.2014.00142.
Olders, Henry. 2003. “Average Sunrise Time Predicts Depression Prevalence.” Journal of Psychosomatic Research 55 (2): 99–105. https://doi.org/10.1016/S0022-3999(02)00479-8.
O’Leary, Eanna. 2009. “Workplace Stress, Sleep Loss and Well-Being: Implications for Public Health Policy.” Summer School 2009, 209. http://www.nuigalway.ie/cisc/documents/issp_summer_school_proceedings_2009.pdf#page=210.
Reynolds, Amy C., and Siobhan Banks. 2010. “Total Sleep Deprivation, Chronic Sleep Restriction and Sleep Disruption.” Progress in Brain Research 185: 91–103. https://doi.org/10.1016/B978-0-444-53702-7.00006-3.
Roenneberg, Till, Karla V. Allebrandt, Martha Merrow, and Céline Vetter. 2012. “Social Jetlag and Obesity.” Current Biology 22 (10): 939–43. https://doi.org/10.1016/j.cub.2012.03.038.
Roenneberg, Till, Tim Kuehnle, Myriam Juda, Thomas Kantermann, Karla Allebrandt, Marijke Gordijn, and Martha Merrow. 2007. “Epidemiology of the Human Circadian Clock.” Sleep Medicine Reviews 11 (6): 429–38. https://doi.org/10.1016/j.smrv.2007.07.005.
Selvi, Yavuz, Adem Aydin, Murat Boysan, Abdullah Atli, Mehmed Yucel Agargun, and Lutfullah Besiroglu. 2010. “Associations Between Chronotype, Sleep Quality, Suicidality, and Depressive Symptoms in Patients with Major Depression and Healthy Controls.” Chronobiology International 27 (9-10): 1813–28. https://doi.org/10.3109/07420528.2010.516380.
Stickgold, Robert, and Matthew P. Walker. 2005. “Memory Consolidation and Reconsolidation: What Is the Role of Sleep?” Trends in Neurosciences 28 (8): 408–15. https://doi.org/10.1016/j.tins.2005.06.004.
Takahashi, Masaya. 2012. “Prioritizing Sleep for Healthy Work Schedules.” Journal of Physiological Anthropology 31: 6. https://doi.org/10.1186/1880-6805-31-6.
Van Cauter, Eve, Karine Spiegel, Esra Tasali, and Rachel Leproult. 2008. “Metabolic Consequences of Sleep and Sleep Loss.” Sleep Medicine 9 Suppl 1 (September): S23–28. https://doi.org/10.1016/S1389-9457(08)70013-3.
Van Dongen, Hans P. A., Greg Maislin, Janet M. Mullington, and David F. Dinges. 2003. “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 (2): 117–26.
Walker, Matthew P., and Robert Stickgold. 2004. “Sleep-Dependent Learning and Memory Consolidation.” Neuron 44 (1): 121–33. https://doi.org/10.1016/j.neuron.2004.08.031.
Williamson, A, and A. Feyer. 2000. “Moderate Sleep Deprivation Produces Impairments in Cognitive and Motor Performance Equivalent to Legally Prescribed Levels of Alcohol Intoxication.” Occupational and Environmental Medicine 57 (10): 649–55. https://doi.org/10.1136/oem.57.10.649.