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Sleep quality (complete darkness, duration, time of day)

Schedule III

Estimated life impact: 3-10 years
Evidence level: Moderate

Last update: 2019-04


Our body needs sufficient sleep to be able to fully rebuild itself from the various physical and psychological stress factors which are affecting us during the waking hours. The amount of sleep needed can vary substantially from person to person, but all humans need some of it.

Quality and function of sleep is a complex matter. There are likely many internal and external factors affecting it. However, sleep is also a very natural process, effects of which are hard to misjudge (much harder than effects of nutrition, for example), but could be hard to notice, and so one of the best ways to evaluate your own personal sleep needs is to just go by how you are feeling before and after the sleep, after trying different kinds of it and seeing how much sleep seems required. If you feel more rested after less hours of sleep of certain quality (in total darkness for instance), that is a high quality sleep for you in your current life circumstances. Such evaluation ability requires developing the natural sensitivity and personal experimentation.

Many studies measure specific hormones like melatonin or cortisol (the main idea being that bad sleep decreases melatonin and increases cortisol, ie the most notorious stress hormone), in order to measure the quality of sleep. Since sleep is very complex, such findings might be a bit simplistic, and need to be taken with caution, but still provide valuable information.

As suggested by common sense, and also seen in conclusions of many research papers on the matter, it’s the overall general sleep pattern that matters – not individual nights or sleep habits during shorter periods of time. Even if you don’t sleep for days sometimes or sleep for 4 hours each day for several weeks – that is not likely to change your fate a lot, assuming that you have an overall proper pattern to back it up with. But longer continuous periods of bad sleep, like sleeping with lights on every day for years – might change your life A LOT. Having regular episodes of quality sleep is of crucial importance, while making sure that EVERY instance of sleep is of high quality is not essential.

Role of sleep in the broad context of personal expansion/enlightenment
The main assumption is that an ideal fully enlightened human being who has achieved a very deep level of consciousness does not need to bother with scheduling sleep etc. It should be relatively obvious to most, that even during episodic flashes of heightened consciousness, during key expansion phases in life, or while having a lot of positive things going on in life, or experiencing events of acute happiness or psychotic motivation (C), quality of sleep is usually not a problem. It’s not something you ever need to put any conscious attention to, because your being just solves all such basic needs for you. Also, such person is not likely to be constrained by too many external factors which would interfere with the natural sleeping process. Lastly, he/she would likely have very few circumstances that would be perceived as stress factors that deplete his/her energy in the first place, and thus their need to sleep and restore would be lower.

However, before getting to that phase, systematic sleep of high quality seems to yield extra resources which can be used to actually achieve such heightened states, and accomplish other more pressing goals faster. The limitations of having a schedule and a couple of rules for sleeping are a cheap price to pay for the extra boost of energy and health to propel you to freedom.

Working on your psychology is the ultimate way to get more energy and resources, but that is a long process and some other steps might help you along the way.

If you are already working on your expansion, a proper schedule will give you more energy to do that (and the extra reserves for the times where you can’t keep the schedule), and if you’re not – then you especially might want to look into a healthy schedule (along with nutrition), since such surface-level measures might just be your only way of consciously and naturally improving your health.


Hazard quantification

How big of a deal is this anyway?

A lot of the hazard in sleep deprivation seems to come from the sheer number of different processes that sleep regulates. While its effect on each individual mechanism in the body might not be huge (even though sometimes it is), when so many of them are affected, the resulting hazard becomes a big problem.

Light at night co‐distributes with incident breast but not lung cancer in the female population of Israel (google scholar cited by 127): 10 year observation study, that yielded that “These results provide coherence of the previously reported case‐control and cohort studies with the co‐distribution of LAN and breast cancer on a population basis. The analysis yielded an estimated 73% higher breast cancer incidence in the highest LAN exposed communities compared to the lowest LAN exposed communities.”



Melatonin-Depleted Blood from Premenopausal Women Exposed to Light at Night Stimulates Growth of Human Breast Cancer Xenografts in Nude Rat (2005) (google scholar 2016 cited by 301) (full pdf)

This study, while technically being ex vivo, is perhaps on of the most substantial ones out there, because they show a clear causation-based connection between melatonin and cancer progression in a controlled trial design. The study took blood from humans who had different amounts of melatonin: from some of them during the day, from others during the night and yet others during a night with a lot of Light-at-Night added (which supposedly suppresses melatonin production and perhaps some other sleep-related hormones). This blood was then used to test progression of cancer cells in living mice.

The increased breast cancer risk in female night shift workers has been postulated to result from the suppression of pineal melatonin production by exposure to light at night. Exposure of rats bearing rat hepatomas or human breast cancer xenografts to increasing intensities of white fluorescent light during each 12-hour dark phase (0-345MW/cm2) resulted in a dose-dependent suppression of nocturnal melatonin blood levels and a stimulation of tumor growth and linoleic acid uptake/metabolism to the mitogenic molecule 13-hydroxyoc- tadecadienoic acid. Venous blood samples were collected from healthy, premenopausal female volunteers during either the daytime, nighttime, or nighttime following 90 minutes of ocular bright, white fluorescent light exposure at 580MW/cm2 (i.e., 2,800 lx). Compared with tumors perfused with daytime- collected melatonin-deficient blood, human breast cancer xenografts and rat hepatomas perfused in situ , with noctur- nal, physiologically melatonin-rich blood collected during the night, exhibited markedly suppressed proliferative activity and linoleic acid uptake/metabolism. Tumors perfused with melatonin-deficient blood collected following ocular exposure to light at night exhibited the daytime pattern of high tumor proliferative activity. These results are the first to show that the tumor growth response to exposure to light during darkness is intensity dependent and that the human noctur- nal, circadian melatonin signal not only inhibits human breast cancer growth but that this effect is extinguished by short-term ocular exposure to bright, white light at night. These mechanistic studies are the first to provide a rational biological explanation for the increased breast cancer risk in female night shift workers. (Cancer Res 2005; 65(23): 11174-84

The most interesting result of this study is that it suggests a direct chemical effect that the melatonin might have on the cancer progression. They even make a point of saying it’s specifically

These  tumor-suppressive  effects  of nighttime-collected, melatonin-rich blood were also totally blocked by the nonselective melatonin receptor (MT1 /MT 2 ) antagonist S20928 (36), indicating that they were, in fact, due to the presence of physiologically elevated levels of circulating melatonin acting via  a  melatonin  receptor–mediated  process.  This  is  further supported by the ability of melatonin, added at a physiologic nocturnal concentration, to melatonin-deficient blood collected following light exposure at night, to restore the tumor-inhibitory responses.

The study does not explicitly state this, but to me it looks like a generic indicator that melatonin levels might have a broad effect on the whole immune system.

I’ve tried to parse this article for some more quantifiable risk assessments or numbers, but they don’t seem to be making any such specific statements. Additionally, since the study is looking at effects in mice, any such assessments would be only speculation anyway.


Mini-review study Melatonin and cancer risk: does light at night compromise physiologic cancer protection by lowering serum melatonin level (2004) (Google scholar 2016 cited by 108)

Two nationwide record linkage studies (Tynes et al, 1996; Hansen, 2001) and a retrospective case–control study (Davis et al, 2001) associated night work with an approximately 50% higher risk of breast cancer. (night work and light-at-night are not the same things, and it has to be very tricky to control for confounding factors, especially in an observational design (working at night has to correlate with a host of other variables and life conditions), but 50% is still a lot. )

Finally, the Nurses’ Health Study, the only prospective study published that evaluated the association, observed a positive association of
extended periods of rotating night work and breast cancer risk […] Thus, in sum, observational studies seem to supportthe hypothesis that night work increases the risk for breast cancer.

evidence from experimental studies strongly suggests a link between melatonin and tumour suppression (Schernhammer and Hankinson, 2003).

In vitro studies do support not only an effect of melatonin on breast cancer (Hill and Blask, 1988; Cos et al, 1996, 1998, 2002; Mediavilla et al, 1999), but also on other tumours. In fact, to date, melatonin has been shown to be oncostatic for a variety of tumour cells in experimental carcinogenesis (Sze et al, 1993; Ying et al, 1993; Petranka et al, 1999; Shiu et al, 1999; Kanishi et al, 2000). Reports show that melatonin exhibits a growth-inhibitory effect on endometrial (Kanishi et al, 2000) and ovarian carcinoma cell lines (Petranka et al, 1999), Lewis lung carcinoma (Mocchegiani et al, 1999), prostate tumour cells (Laufer et al, 1999), and intestinal tumours (Anisimov et al, 1997, 2000a, b), for example. Furthermore, today, several clinical trials confirm the potential of melatonin, either alone or in combination with standard therapy regimens, to generate a favourable response in the treatment of human cancers (Vijayalaxmi et al, 2002).

In these analyses, women who worked 15 or more years on rotating night shifts were at a higher risk of colorectal cancer than were women who never worked rotating night shifts. The relative risks after adjustment for age, smoking, physical activity, and other colorectal cancer risk factors were 1.00 (0.84–1.19) for 1–14 years on rotating night shifts and 1.35 (1.03–1.77) for 15 or more years on rotating night shifts (test for trend, P0.04).


Interestingly, less sleep seems to make people hungrier. Sleep restriction leads to increased activation of brain regions sensitive to food stimuli (Google scholar: cited by 108)

Background: Epidemiologic evidence shows an increase in obesity concurrent with a reduction in average sleep duration among Americans. Although clinical studies propose that restricted sleep affects hormones related to appetite, neuronal activity in response to food stimuli after restricted and habitual sleep has not been investigated.

Objective: The objective of this study was to determine the effects of partial sleep restriction on neuronal activation in response to food stimuli.

Design: Thirty healthy, normal-weight [BMI (in kg/m2): 22–26] men and women were recruited (26 completed) to participate in a 2-phase inpatient crossover study in which they spent either 4 h/night (restricted sleep) or 9 h/night (habitual sleep) in bed. Each phase lasted 6 d, and functional magnetic resonance imaging was performed in the fasted state on day 6.

Results: Overall neuronal activity in response to food stimuli was greater after restricted sleep than after habitual sleep. In addition, a relative increase in brain activity in areas associated with reward, including the putamen, nucleus accumbens, thalamus, insula, and prefrontal cortex in response to food stimuli, was observed.

Conclusions: The findings of this study link restricted sleep and susceptibility to food stimuli and are consistent with the notion that reduced sleep may lead to greater propensity to overeat. This trial was registered at clinicaltrials.gov as NCT00935402.

Conclusions: The findings of this study link restricted sleep and susceptibility to food stimuli and are consistent with the notion that reduced sleep may lead to greater propensity to overeat.


Then of course, specific health hazards might not be the only reasons to increase the quality of sleep: if the sleep process itself is less potent, it’s very natural to assume that you are going to need more of it. (Or be more tired after the same fixed amount of sleep, and indirectly sleep more during the day by being more tired.) Seeing it this way, low-quality sleep literally takes your time away, by requiring more time for sleep instead of being awake and being able to do stuff.

More research is needed

Most of the studies are observational, and most cited studies that try to group and categorize previous research basically all say that more research is needed. Sleep is a tricky thing to study, and the research should be used as guidelines, and you should try some of the things they suggest for yourself and see if it works for you. When it comes to sleep, it is relatively hard to misjudge your own subjective perception of it’s quality.


You should sleep in total darkness, since even small amounts of light interfere with sleep

At this point I am assuming that it is pretty obvious that you should sleep in a somewhat dark place at least (for example Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans, google scholar cited by 149). The notion that light interferes with the sleep generally, and with melatonin levels specifically (and that it’s levels can decrease in very short time after exposure to light) can be found in virtually any scientific (and popular) contemporary publication, and there is no known research that contradicts this. It is also very easily confirmed personally: sleeping with a lot of lights on is just not that comfortable.

A big chunk of current (2016) research that states that even small amounts of light are detrimental to good sleep is based on mice or hamsters:
Chronic dim light at night provokes reversible depression-like phenotype: possible role for TNF (Google scholar 2016 cited by 28).
Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters (Google scholar 2016 cited by 57).
Aberrant light directly impairs mood and learning through melanopsin-expressing neurons (Google scholar 2016 cited by 113).

Hamsters are surely mammals and likely share a lot of life problems with humans, but it’s a bit questionable that there are so few good studies on humans. But then again, hamsters are easier to test on so that might be a reason.


At this time, to me it seems that scientific evidence for the dangers of even dim lights during the night is somewhat limited but substantial.

The evidence does seem to show that bright lights are even worse (and really this should be very obvious to you from your own experience), but even dim lights do have an effect.


Blue light at night is more dangerous than warm red lights

(a report) http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side

“Dr. Charles Czeisler of Harvard Medical School showed, in 1981, that daylight keeps a person’s internal clock aligned with the environment.”

“While light of any kind can suppress the secretion of melatonin, blue light does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).”


Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans (2009) (Google scholar 2016: Cited by 88)

A comparison of mean melatonin suppression with 40 μW/cm2 from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.

The results seem to show that exposure to blue light from a LED-panel (of approximately 500 lux, converting their units) could decrease plasma melatonin levels by more than 50%. Also “The graph also demonstrates the mean percent change for a 40 μW/cm2 exposure with a 4,000 K lamp is numerically very similar to suppression at 10 μW/cm2 on the blue LED panel.

It seems that blue light is about 4 times stronger at decreasing melatonin levels than a broad spectrum 4000K lamp.


Some additional links


“Polychromatic light was more effective at suppressing nocturnal melatonin than monochromatic blue light matched for melanopsin stimulation, implying that the melatonin suppression response is not solely driven by melanopsin. The findings suggest a stimulatory effect of the additional wavelengths of light present in the polychromatic light, which could be mediated via the stimulation of cone photopigments and/or melanopsin regeneration.”


A very common but perhaps valuable to some people conclusion from the results of most of existing research is that in practice, regularity of sleep is important. No matter what the conditions of your sleep are when it happens, the body’s clock will try to put you to sleep during certain time. If you try to sleep during different hours each day, that clock will fight with the reality, resulting in poorer sleep quality overall. Simplifyingly, it will not release enough of the sleep hormones during your sleep, because it is used to releasing them at a different time. Try to sleep at the same time of day each day.

It’s difficult to quantify this parameter based on current research (there is no reliable data), so you’ll have to test for it.

Based on the little research there is, and on personal observations and intuitions about sleep, sleeping properly (in darkness, etc.) is more important than regularly, but you should do both.

Sleep during certain hours

Many studies and researchers mention that it’s not only important to sleep in the dark, but to also see the light while you’re awake. It’s not only about the nights being dark, it’s more generally about being a friend with your internal clock. So that it will release the sleep hormones when the body is coming into a rebuilding phase. If you expose yourself to a lot of proper light during the day, that thing in itself calibrates and sets the clock. So you need to get a lot of light while you’re awake.

While there is no research that I’ve seen that can actually show that sleeping during certain specific hours of day is important (it’s more about regularity and light exposure; sleeping during the same periods each day, whatever those periods are), if you sleep (even in darkness) during light hours of the day, it will be harder for you to be exposed to bright light during your waking hours, which will mess with the clock. For some, the easiest way to combat this is simply to sleep when the sun is down and be awake when it’s up. It’s very hard to quantify how much this matters though. Likely this is much less important than the rest.

TODO: Melatonin pills?

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