• Core Finding: Sleep regularity (the day-to-day consistency of when you sleep and wake) is a significantly stronger predictor of premature mortality risk than total sleep duration.
• Study Design: Researchers analyzed over 10 million hours of objective accelerometer data from 60,977 UK Biobank participants (average age 62.8 years) over a 1-week period, with a median follow-up of 6.3 years.
• Sleep Regularity Index (SRI): Calculated based on the probability of a participant being in the same state (asleep or awake) at any two time points 24 hours apart.
• Mortality Reductions: Compared to the most irregular sleepers (lowest quintile), those in the top four quintiles of sleep regularity had:
  • 20% to 48% lower risk of all-cause mortality.
  • 16% to 39% lower risk of cancer mortality.
  • 22% to 57% lower risk of cardiometabolic mortality.
• Confounder Control: Associations remained robust even after adjusting for age, sex, ethnicity, socioeconomic factors, lifestyle choices, and existing health conditions.
• Implications: While traditional guidelines emphasize sleep duration (7 to 9 hours), targeting consistent day-to-day sleep timing may be a simpler, more effective way to support circadian rhythms and lower mortality risk.

Hacker News Discussion

• Magnesium Supplementation: Several users noted that correcting a magnesium deficiency (especially using magnesium L-threonate or liquid formats) dramatically improved muscle relaxation and resolved sleep onset issues.
• Melatonin Dosing Nuances: A highly discussed thread focused on the typical over-dosing of melatonin. While retail stores frequently sell 5–30mg doses, commenters pointed out that physiological/micro-dosing (0.1mg to 0.3mg, or up to 1mg via liquid/cut gummies) is far more effective and prevents morning grogginess or dependency.
• Sleep Architecture & Modern Living: Users referenced historic sleep patterns (such as segmented "first" and "second" sleep) and highlighted how modern employment schedules, artificial blue light, and constant cognitive stimulation disrupt natural circadian rhythms.
• Waking Up During the Night: Commenters shared practical mitigation strategies for middle-of-the-night waking, such as using passive audiobooks to distract a spinning mind, as well as screening for obstructive sleep apnea if frequent awakenings persist.

• The Cause of Post-Sleep Fatigue: Waking up tired, sluggish, or with a mild headache after sleeping with the air conditioner on is often caused by high carbon dioxide (CO2) accumulation in a sealed bedroom, rather than the AC unit itself.
• The Mechanism of CO2 Buildup: Most residential air conditioners only circulate and cool internal air instead of drawing fresh air from outside. When doors and windows are completely closed to preserve cold air, the CO2 exhaled by sleepers (roughly 15 to 20 liters per hour per adult) builds up continuously.
• Impact on Sleep Quality: While outdoor CO2 levels rest around 400 ppm, an enclosed 20m² bedroom can spike to 1,500–2,000 ppm over 7 to 8 hours. Levels above 1,000 ppm cause shallower sleep and frequent awakenings, while levels past 2,000 ppm prompt morning headaches, dry mouth, and low alertness.
• Vulnerable Populations: Elderly individuals, young children, and people suffering from chronic respiratory conditions, asthma, or cardiovascular diseases are significantly more sensitive to stuffy, high-CO2 environments.
• Misconceptions Debunked: Air purifiers filter fine dust, allergens, and odors but are entirely incapable of removing CO2. Additionally, social media claims linking normal bedroom CO2 levels to severe issues like hair loss or brain damage are not scientifically proven.
• Simple Mitigation Strategies: Experts recommend opening a bedroom door or window by just a few centimeters to allow constant air exchange without significantly sacrificing room temperature. Alternatively, using small exhaust fans or dedicated fresh-air ventilation systems resolves the issue.

• Blue light filters and "blue-blocker" lenses are largely ineffective for reducing digital eye strain or significantly improving sleep quality.
• Most digital screens emit less than 0.4% of the blue light levels found in natural daylight, making the "hazard" from screens negligible compared to outdoor exposure.
• Clear blue-blocking lenses typically only filter about 10–25% of blue light; for a filter to be clinically significant, it would require a heavy amber tint that noticeably alters color perception.
• Digital eye strain is more likely caused by the way we use screens—such as reduced blinking and prolonged focus—rather than the blue light itself.
• While blue light suppresses melatonin, the total brightness (luminance) of a device and the engaging nature of the content are more significant factors in sleep disruption than the specific color spectrum.
• Experts recommend better screen habits, such as the 20-20-20 rule and matching monitor brightness to room lighting, as more effective solutions than specialized eyewear.

Hacker News Discussion

• Anecdotal Success vs. Scientific Rigor: Many commenters shared personal success stories, claiming immediate relief from eye strain when using software like Flux or physical filters, often dismissing the article's skepticism as "vibes-based" rather than considering the users' subjective comfort.
• Mechanism of Action: A major point of debate was whether the perceived benefits are actually due to blue light reduction or a secondary effect of reducing total screen luminance.
• Placebo Effect: Some users argued that even if the benefits are a placebo, the subjective improvement in comfort and sleep makes the tools worthwhile for the individual.
• Critique of the Article: Critics argued the blog post relied too heavily on theoretical mechanisms rather than high-quality clinical trials, noting that "absence of evidence is not evidence of absence."
• Alternative Solutions: Discussion participants recommended lowering monitor brightness to match a piece of white paper held next to the screen and using bias lighting to reduce contrast strain.

• CBT-I Therapy Foundations: The primary method for treating insomnia is Cognitive Behavioral Therapy for Insomnia (CBT-I), which focuses on changing sleep-related behaviors and beliefs rather than just basic hygiene.
• Sleep Compression/Restriction: One of the most effective techniques is paradoxically shortening the time spent in bed (e.g., to 5.5–6 hours). This builds "sleep pressure" and prevents the brain from associating the bed with anxiety and wakefulness [00:10:32].
• The Sleeping Pill Trap: Drugs like benzodiazepines and "Z-drugs" do not treat the underlying causes of insomnia; they merely "shut down" the nervous system. Long-term use can disrupt sleep architecture, hinder brain detoxification, and lead to dependency [00:30:08].
• Light and Circadian Rhythm: Natural daylight is the strongest regulator of the sleep-wake cycle. Morning sun exposure and avoiding bright light in the evening help natural melatonin production [00:17:41].
• Shift Work Strategies: Shift workers should simulate night conditions after finishing work by wearing sunglasses on the way home and using blackout curtains to ensure restorative sleep during the day [00:18:15].
• Orthosomnia and Wearables: Obsessively tracking sleep data via smartwatches can paradoxically worsen sleep quality. This "orthosomnia" creates anxiety when users see "bad" scores, leading to further sleep interference [00:50:23].
• Mental Offloading: It is crucial to "unload" the mind before bed. Techniques like writing down worries or the next day's to-do list during the early evening (outside of the bedroom) help prevent racing thoughts at night [01:10:09].
• Individualized Relaxation: Methods such as Jacobson’s Progressive Muscle Relaxation or even nature observation (e.g., birdwatching) can lower the nervous system's overall arousal levels [01:13:14].

• Insomnia is a Common Problem: Insomnia is widespread, though increased awareness makes it seem like a modern issue. It's often triggered by stressful life events (e.g., divorce, job loss) [00:03:39], [00:21:03].
• The Danger of Counter-Intuitive Habits:
  • Do not try to "delete thoughts" when you can't sleep, as this is counterproductive [00:00:07], [00:28:34].
  • Do not mistake light sleep (N1) for being awake; people often underestimate their total sleep time [00:16:19].
  • Attempting to "catch up" on sleep (going to bed early, sleeping in) destroys the crucial sleep pressure (ciśnienie na sen) [00:22:39].
• Core Principles of Sleep Therapy (CBT-I):
  • Fixed Wake-up Time is Key: The most important rule is to maintain a consistent wake-up time, varying it by no more than an hour, even on weekends [00:25:55].
  • Sleep Restriction: If you spend 8.5 hours in bed but only sleep 6, the initial goal is to restrict your time in bed to 6 hours to build up sleep pressure [00:24:12], [00:26:15].
  • Stimulus Control: If you cannot fall asleep after 20 minutes (or wake up at 3 AM), get out of bed and engage in a calming, non-stressful activity (like watching a show or reading) until you feel intensely sleepy, then return to bed [00:29:09].
• Consequences of Sleep Deprivation:
  • Relationships: Lack of sleep increases the risk of divorce, reduces empathy, and makes couples argue worse [00:09:44], [00:10:14].
  • Health and Cognition: It weakens the immune system (doubling the risk of catching a cold) [00:11:37], drops testosterone levels (by 10-15%) [00:12:07], impairs strong willpower, leads to worse decision-making, and increases the craving for junk food [00:14:30], [00:31:32].
  • The "3 AM Brain" operates with low positive and high negative affect; do not make major life decisions or ruminate during this time [00:30:12], [00:30:48].
• Medication and Chronotypes:
  • Zolpidem (Z-drugs) is generally not recommended for primary insomnia, as its side effects (e.g., amnesia, accidents, increased depression/suicidal thoughts) can be more severe than the insomnia itself [00:36:49].
  • Chronotypes (larks vs. owls) are genetically determined; waking up at 5 AM is a development guru myth that can be harmful for "owls" [00:55:12], [00:56:44]. Owls and adolescents benefit from later school/work start times [00:59:21], [01:00:13].
• Managing Shift Work:
  • Shift work increases health and mental health risks [00:43:15].
  • Strategies: Nap for 1-1.5 hours before the night shift, use caffeine only in the first half of the night, eat well during the shift, and get a small nap (20 minutes) if possible [00:48:26], [00:49:55], [00:51:00].
  • Day sleep is always worse than night sleep; it's recommended to accept a shorter day sleep to get daylight exposure and physical activity later, which helps regulate the circadian rhythm [00:52:02], [00:52:48].
• Dreams: Dreams help the psyche process daily events and emotions [01:07:05]. If you have recurring nightmares, use Imagery Rehearsal Therapy (IRT): change the end of the nightmare, write down the positive new ending, and visualize it daily for 10-15 minutes [01:08:42].

• Eating timing matters: Stop eating at least 3 hours (ideally 10) before bed to boost HRV; late eating harms recovery.
• Diet quality: Higher HRV is associated with diets high in fish, vegetables, and fruit, and avoiding processed foods, seed oils, and high sodium.
• Consistency over specific diet types is key; less processed food and fewer calories help HRV (unless you're a performance athlete).
• Aerobic, endurance, and high-intensity interval training all increase HRV, with aerobic exercise having the most effect.
• Endurance training improves baroreceptor control and vagal tone; 1-2 sessions weekly recommended.
• High-intensity intervals (above 90% max HR) boost parasympathetic activity and HR recovery; occasional sessions are best.
• Weightlifting contributes less to HRV, but mixing it with more aerobic and interval work is optimal.
• Sleep greatly impacts HRV: Consistent bedtime, getting morning sunlight, daytime exercise, and avoiding late meals all help.
• Wind down 30 minutes before sleep; use breathing techniques like "box breathing" to relax and fall asleep quicker.
• Optimize sleep environment: Cool room (67°F), blackout curtains, calming music, mouth tape for nasal breathing.
• Sauna use increases plasma volume and can help HRV, as does cold exposure (cold showers/plunges) by providing hormetic stress.
• Devices (e.g., Petto for vagus nerve stimulation) may help but some like Sensate may be placebo.
• Reducing stress is crucial—doing meaningful work, fulfilling relationships, and low chronic stress (example: Warren Buffett).
• Combining diet, exercise, great sleep, minimal stress, and some environmental exposures (sauna/cold) is the best strategy for sustainably higher HRV.

Why sleep tracking may not make any sense

• for health - sleep apnea - silent acid reflux connection

• health - sleep apnea - silent reflux connection

  • if you have sleep apnea and you are experiencing post nasal drip, coughing, clearing throat etc, that is the acid coming up from your stomach and obstructing breathing

• for: health - sleep apnea, sleep apnea - acid reflux - laryngopharyngeal reflux, sleep apnea - slient reflux connection

• comment

  • symptoms
    • sleep apnea, silent reflux, post nasal drip, coughing,

Page with many resources on - Learning - Creativity - Intelligence - Sleep - Education - Memory - Health - Productivity - Myths - SuperMemo - Older texts

Schreiber, M. (2022, February 18). Covid infection increases risk of mental health disorders, study finds. The Guardian. https://www.theguardian.com/world/2022/feb/18/covid-infection-increases-risk-mental-health-disorder-study

this is a great question - reminder to self to do more research on this

While this is interesting analysis, I wonder if it's close to the best data we have on this.

Personally as a bipolar person, I can say this definitely correlates with my experience! You could maybe add my experience to the data: + Severe mania - 0-3 hours avg (often in involuntary naps) + Hypomania - 1-5 hours avg (w/ all-nighters) + Elevated/sub-hypomania - 5 hours avg + Stable - 6-8 hours avg + Depressive - 8-10 hours avg + Severe depression - 10-16 hours avg

while this is a good list and a valuable thought experiment, it also misses the features that made sleep 10,000 years ago easier and more effective: + Far better diets on average than Western person + No blue light / constant digital stimulation + Extremely active lifestyles with lots of exercise, makes sleep easier + Natural attunement to circadian rhythms that comes with waking up & sleeping w/ dusk & dawn + Lower stress and lower levels of psychopathology on average? Better resilience to stress? + Other things

This may explain why we "need" the hyper-comfortable modern sleep, more than we used to need it

This sounds a bit hyperbolic, unlikely a scientific paper would use this language. Also unclear what it means for brains to be "overwhelmed with pleasure," or what objective scientific criteria for what shows something is a "superstimulus" are.

Nursing professionals are facing with severe sleep problems during the covid 19 pandemic time. Nurses were asked to work in an environment that had a more increased level of risk than ever before. Depression and anxiety from the workplace could affect the confidence of healthcare workers in themselves as well as general trust in the healthcare system. This will lead to their turnover intention which may undermine the efforts of the governments to control the COVID-19 pandemic. The rising concern may change the working schedules of healthcare workers, offering more occupational healthcare support.

Muth, A., Vermeer, A. L., Terenzi, D., & Park, S. Q. (2021). The impact of diet and lifestyle on wellbeing during COVID-19-lockdown. PsyArXiv. https://doi.org/10.31234/osf.io/erta5

Short afternoon naps at the workplace lead to significant increases in productivity, psychological well-being and cognition. In contrast, an extra 30 minutes sleep at night shows no similar improvements. [Pedro Bessone]

Franceschini, C., Musetti, A., Zenesini, C., Palagini, L., Pelosi, A., Quattropani, M. C., Lenzo, V., Freda, M. F., Lemmo, D., Vegni, E., Borghi, L., Saita, E., Cattivelli, R., De Gennaro, L., Plazzi, G., Riemann, D., & Castelnuovo, G. (2020). Poor quality of sleep and its consequences on mental health during COVID-19 lockdown in Italy [Preprint]. PsyArXiv. https://doi.org/10.31234/osf.io/ah6j3

Hisler, G., & Twenge, J. (2020). Sleep health in U.S. adults before and during the COVID-19 pandemic [Preprint]. PsyArXiv. https://doi.org/10.31234/osf.io/bzqhd

Kiltie, J., Satchell, L., M. (929493), C., Daniels, M., Gould, C. S., Sparrowe, K., Hudson, C. A., & Husted, M. (2021). The effect of change in routine on student mental wellbeing during a nationwide lockdown. PsyArXiv. https://doi.org/10.31234/osf.io/suwnp

Becker, S. P., Dvorsky, M., Breaux, R., Cusick, C., Taylor, K., & Langberg, J. (2021). Prospective Examination of Adolescent Sleep Patterns and Behaviors Before and During COVID-19. PsyArXiv. https://doi.org/10.31234/osf.io/yzd4m

https://www.albany.edu/~drewa/health/practices.html

• Neuroscientists achieve the unthinkable - talking to someone who’s asleep, and they’ve already done it with several people.
• Cross-national research team demonstrated two-way communication with lucid dreamers in the REM (rapid eye movement) sleep phase.
• Eye movements generate current, which is recorded by electrodes placed around the eyes, and the signals are translated to dialogue.
• Studying the mind during sleep used to be limited to people telling stories about their dreams after waking up, so this is a big gamechanger.
• Psychology experiments with sleeping people are now possible, and it could greatly enhance our understanding of consciousness and the mind’s abilities.

• Whether you perform best in the morning or evening depends on your chronotype - ‘larks’ work early, ‘night owls’ work late.
• Because night owls go to sleep later but have to get up early with everyone else, they incur sleep debt and need catch-up sleep on non-work days, which is bad for health.
• To explore this, researchers used data from a 1966 Finland birth cohort study, initially consisting of 12,058 children.
• At age 46, 2672 men and 3159 women from the study were questioned about their chronotypes in 2012, and monitored for 4 years afterwards.
• Compared to larks, owls had worse ratings for variables related to sleep and health, and were twice more likely to underperform at work.

Gupta, Ravi, Sandeep Grover, Aniruddha Basu, Vijay Krishnan, Adarsh Tripathi, Alka Subramanyam, Anil Nischal, et al. “Changes in Sleep Pattern and Sleep Quality during COVID-19 Lockdown.” Indian Journal of Psychiatry 62, no. 4 (2020): 370–78. https://doi.org/10.4103/psychiatry.IndianJPsychiatry_523_20.

Wright, Kenneth P., Sabrina K. Linton, Dana Withrow, Leandro Casiraghi, Shannon M. Lanza, Horacio de la Iglesia, Celine Vetter, and Christopher M. Depner. “Sleep in University Students Prior to and during COVID-19 Stay-at-Home Orders.” Current Biology 30, no. 14 (July 20, 2020): R797–98. https://doi.org/10.1016/j.cub.2020.06.022.

Rogers, Andrew H., Lorra Garey, and Michael J. Zvolensky. “COVID-19 Psychological Factors Associated with Pain Status, Pain Intensity, and Pain-Related Interference.” Cognitive Behaviour Therapy, February 10, 2021, 1–13. https://doi.org/10.1080/16506073.2021.1874504.

Finding it hard to sleep might be either because of the blue light or the psychological effect of screens on us

Marmet, S., Wicki, M., Gmel, G., Gachoud, C., Daeppen, J.-B., Bertholet, N., & Studer, J. (2020). The psychological impact of the COVID-19 crisis on young Swiss men participating in a cohort study. PsyArXiv. https://doi.org/10.31234/osf.io/kwxhd

Summary of the article:

• We spend nearly half of each day daydreaming, and usually think that it’s a bad thing, but it turns out that highly demanding tasks make us daydream more.
• It allows us to turn off our surroundings, and can be a way of imagining solutions to the problem at hand.
• To find this out, researchers did two studies of employees and managers in South America, including mainly surveys about daydreaming.
• Daydreaming turned out to happen more when the tasks required a lot of focus - it can boost creative problem-solving as long as we’re personally invested in our work.
• However, for people who don’t identify with their work, daydreaming was linked to worse performance.

COVID-19 and the Labor Market. (n.d.). IZA – Institute of Labor Economics. Retrieved October 10, 2020, from https://covid-19.iza.org/publications/dp13569/

IZA – Institute of Labor Economics. ‘COVID-19 and the Labor Market’. Accessed 6 October 2020. https://covid-19.iza.org/publications/dp13715/.

The COVID-19 Pandemic Is Changing Our Dreams—Scientific American. (n.d.). Retrieved September 29, 2020, from https://www.scientificamerican.com/article/the-covid-19-pandemic-is-changing-our-dreams/

Maintaining health and wellbeing during the COVID-19 pandemic | Institute of Psychiatry, Psychology & Neuroscience | King’s College London. https://www.kcl.ac.uk/ioppn/maintaining-health-and-wellbeing-during-the-covid-19-pandemic

Lebel, C., MacKinnon, A., Bagshawe, M., Tomfohr-Madsen, L., & Giesbrecht, G. (2020, April 23). Elevated depression and anxiety among pregnant individuals during the COVID-19 pandemic. https://doi.org/10.31234/osf.io/gdhkt

Cellini, N., Canale, N., Mioni, G., & Costa, S. (2020, April 11). Changes in sleep pattern, sense of time, and digital media use during COVID-19 lockdown in Italy. https://doi.org/10.31234/osf.io/284mr

Rosen, Z., Weinberger-Litman, S. L., Rosenzweig, C., Rosmarin, D. H., Muennig, P., Carmody, E. R., … Litman, L. (2020, April 14). Anxiety and distress among the first community quarantined in the U.S due to COVID-19: Psychological implications for the unfolding crisis. https://doi.org/10.31234/osf.io/7eq8c

This is super helpful. Bold

This is super helpful.