Information on sleep's importance and hygiene. See personal sleep suggestions here.
I probably don't get enough sleep. At the time of writing (09 September 2022), my last two weeks of sleep (measured as time in bed, not actually time spent asleep) have been 5, 6, 8, 8, 7, 8, 7, 6, 6, 5, 6, 6, 4, and 6 hours. That span of 8-8-7-8 was because of a three-day weekend and working from home on the following day. I wake up exhausted and often convince myself to set another alarm for 10 minutes, despite knowing full well it won't help. My energy gets to regular levels by mid-morning and stays that way until late evening. I don't consume caffeine.
Yet I refuse to go to bed earlier. I know I should, but I don't. Why? I have too much to do and sleep is for those who live boring lives.
My life is pretty busy because of my own choosing. My average weekday looks like such:
Sometimes I get off work around 4:00pm, sometimes I don't have many hobbies to do, sometimes my training sessions last 1:30 hr or even 2:30 hr, sometimes I have to finish up extra work in addition to my to-do items. Life comes down to priorities and I seem to have too many, but none that I'm willing to give up. This leads to sleep going onto the chopping block.
I've also (probably) bought too far in to the "sleeping in is wasting the day" mindset many people hold. I still believe in this: getting 10-12 hours of sleep is wasting the hours one could be awake experiencing the world and all it has to offer. However, that doesn't lead to the conclusion that sleep duration should be minimized as much as possible while still maintaining some semblance of sanity and motor functions. MacAskill's The philosophical case against oversleeping does an excellent job of summing up my thoughts, but I took it an extra step and ignored her point about getting the sleep one needs, because need and need are two different things.
So why write this post? Two reasons.
First, I feel like my cognitive abilities have declined over the past year, and in reviewing my sleep logs, it follows a general lack of sleep. I occasionally have brain fog at work when someone asks me a question and I can't think of the answer. I miss what I think are grossly obvious observations or notes (I think this is more of a answer-being-obvious-after-being-shown type of effect, but who really knows). If I can get a better idea of the positive and negative effects of sleep and lack of sleep, respectively, then the part of me that stays up late may be more amenable to getting to bed early.
Second, and as a result of the first reason, my aerobic and strength training will almost certainly improve with more sleep.
A list of unresearched, general benefits from improving my sleep (in rough order of personal importance):
Sleep hygiene is not as well-known as it probably should be given its impact on sleep quality. Sleep is not entirely about quantity, but also quality, which is based on sleep hygiene practices. Here I explore common sleep hygiene suggestions' purpose and effectiveness. All subsections are stated as the suggestion, e.g., "Not Eating Before Bed" means the best sleep hygiene practice is to not eat before bed. Each section has practical suggestions at the end.
The following are ordered from I determined to be most to least important.
The type of food/drink absolutely matters. Low-calorie consumption is mostly fine. Foods/drinks with caffeine, such as chocolate or coffee, can cause one to wake up during the night or even prevent them from falling asleep altogether, leading to less sleep and their sleep schedule being disrupted. Caffeine blocks adenosine, which increases the need for sleep.
There is a hypothesis that tryptophan, an amino acid present in milk and meats, among other foods, induces sleepiness. This is largely considered a myth.
Some highlights from Kinsey and Ormsbee's The Health Impact of Nighttime Eating: Old and New Perspectives (annotated PDF):
studies in free-living healthy adults have shown that meal satiety also varies with time of day and that food intake during the night is less satiating and leads to greater daily caloric intake compared to food consumed in the morning hours
data is beginning to mount to suggest that this finding is not consistent if the food choice is altered to favor small, nutrient-dense, low energy foods and/or single macronutrients (<200 kcals)
Compared to the placebo group, those receiving the casein before sleep had higher plasma essential amino acid concentrations indicating that protein ingestion before sleep was effectively digested and absorbed. The increase in amino acid availability translated to higher whole-body and muscle protein synthesis rates (~22%, Figure 1A) and a net positive protein balance during the overnight period in the group receiving protein compared to the placebo control [52].
the data suggest that it may be advantageous for active individuals to consume a small, nutrient dense, high protein beverage (~150 kcals) before bed [47,52]. It is plausible to hypothesize that acute enhancements in overnight muscle protein synthesis and next morning resting metabolism may further aid in the maintenance of and/or improvement in body composition and thereby provide a competitive advantage in healthy, physically active individuals
Sadly, this focuses more on health impacts (I know it's the title) than sleep impacts, but is still extremely useful. I could not find literature on the impact of nighttime eating and sleep quality that didn't focus on a certain population.
Lockley et al.'s High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light finds that:
Exposure to 6.5 h of monochromatic light at 460 nm induces a two-fold greater circadian phase delay than 6.5 h of 555 nm monochromatic light of equal photon density. Similarly, 460 nm monochromatic light causes twice the amount of melatonin suppression compared to 555 nm monochromatic light, and is dependent on the duration of exposure in addition to wavelength.
To clarify, blue light ranges from 450-495 nm wavelengths, where green ranges from 495-570 nm. To summarize, Lockley et al. found that wavelengths near the blue-green range suppress melatonin and cause a circadian rhythm delay.
Zhao et al.'s Red Light and the Sleep Quality and Endurance Performance of Chinese Female Basketball Players found that:
red-light treatment improved the sleep, serum melatonin level, and endurance performance ... found a correlation between changes in global Pittsburgh Sleep Quality Index and serum melatonin levels (r = −0.695, P = .006)
Despite searching for a good bit, I could not find the physiological explanation behind why red light promotes melatonin production. I've heard a theory that's it evolutionary: our ancestors headed to bed when sunset was happening because it was too dangerous to stay out.
A consistent (read: healthy) sleep schedule almost entirely comes down to discipline, with the exception of those who have circadian rhythm sleep disorders. This is the discipline to maintain sleep and wake times, to not nap, to avoid certain substances, etc.
A quick primer on circadian rhythms, which dictate one's natural sleep schedule: circadian rhythms are the body's 24-hour "clocks" that regulate certain functions and behaviors. This includes digestion, body temperatures (as mentioned in the paper, "rhythms of core body temperature and sleep propensity vary inversely across the day and night in healthy young adults"), and hormone release:
Several hormones were shown to have daily oscillations, and among these the best characterised are melatonin, cortisol, gonadal steroids, prolactin, thyroid hormone and growth hormone (GH). The so-called nutrient-sensitive hormones, namely insulin, leptin, ghrelin and adiponectin also oscillate on a circadian basis, and their release is, at least in part, regulated by environmental stimuli, such as feeding time and light–dark cycles.
All of these different sub-rhythms connect to the so-called circadian pacemaker, or the suprachiasmatic nucleus (SCN) of the hypothalamus. Light has a significant effect on the SCN:
exposure to a cyclic light stimulus can induce strong (type 0) resetting of the human circadian pacemaker, indicating that exposure to light affects the pacemaker's amplitude of oscillation as well as its phase ... response of the circadian pacemaker to light depends not only on the timing, intensity and duration of light exposure, but also on the number of consecutive daily light exposures ... properly timed exposure to light can reset the human clock to any desired hour within one to three days
It's important to note that chronotypes—"the natural inclination of your body to sleep at a certain time"—exist at a genetic level and can only be trained so much in either direction.
One's bed, and preferably bedroom altogether, should only be associated with sleep, and if really needed, sex. Nothing else. No browsing the internet, no calling friends, no watching movies. Sleep and sex. That's it.
The University of Massachusetts offers sleep scheduling and stimulus control techniques here:
Stimulus control techniques are deigned to reduce the brain’s association between the bed and wakefulness while increasing the association between the bed and sleep. By making the bed a stronger cue for sleep, you will more readily fall asleep and stay asleep.
Step 1: Use your bedroom for sleep and sexual activity only. Do not use your bed and bedroom to study or talk on the telephone, or as your primary room for watching television, etc. Your goal is to associate your bed with sleep, not wakefulness.
Step 2: Limit awake time in bed to one half hour both before lights go out and after your final awakening in the morning. If you like to read or watch television in bed before bedtime as a transitional activity, limit this to 20-30 minutes. Similarly, get out of bed in the morning within 20- 30 minutes of your final awakening. Remember, your goal is to associate your bed with sleep, not wakefulness.
Step 3: Make sure you feel drowsy when you turn off the lights to go to sleep. Otherwise, you are more likely to lie awake and think. Learn to rely on internal cues as indicators of drowsiness (such as eyes closing, head nodding) rather than external cues such as the clock or your partner’s bedtime. If you go to bed at the same time every night, you are probably relying on external cues since it is unlikely you get drowsy at the same time every night. (Since you will be reducing the time that you allot for sleep by going to bed later or getting up earlier, you will be more likely to feel drowsy at bedtime.)
Step 4: If you do not fall asleep within 20-30 minutes, or if you awaken during the night and do not fall back to sleep within that time and are wide awake, do not lie in bed tossing and turning. (Also, since you should not focus on the clock, the 20-30 minute guideline should be estimated.) Instead, go to another room and engage in a quiet, relaxing activity (watching television or reading a magazine or book) for at least 30 minutes or until you feel drowsy, then attempt to go to sleep again. Repeat this procedure as often as necessary until you fall asleep. You can also stay in bed and read when you cannot sleep as long as you go back to sleep in a half hour; otherwise, you will associate your bed with wakefulness. This is called the “1/2 hour-1/2 hour rule”.
The Sleep Foundation offers bedroom design tips that help facilitate healthy sleep here:
Blackout curtains can help if your room receives lots of exterior light. Lighting, including a bedside lamp if you use one, shouldn’t be too bright. Lighting with a low color temperature and illuminance can make it easier to feel drowsy and doze off. ... If you need to keep a device in your bedroom, try to keep it out of arm’s reach and avoid using it for an hour or more before bedtime. [Also, making sure any lights outside the bedroom are off, or at least not leaking through the door.]
External noise can cause frequent awakenings, and these disruptions have been tied to reduced levels of both sleep quality and overall health . If outside noise is beyond your control, a white noise machine may help drown the sounds out.
Your bedroom temperature should be comfortable, usually somewhere between 60 to 71 degrees Fahrenheit (15.6 to 22.0 degrees Celsius). Excess heat can disrupt sleep , so most experts suggest erring on the side of a cooler bedroom.
Your mattress should be well-built and comfortable, meaning that it meets your personal firmness preference. It should also be supportive and provide appropriate pressure point relief to suit your body weight and sleeping position. A new mattress can be a significant investment, but research has found that it can improve sleep and decrease stress and back pain . Not surprisingly, the National Sleep Foundation found in its 2010 Bedroom Poll that 93% of people said a comfortable mattress was important to getting quality sleep. In addition to your mattress, your pillows, sheets, and blankets play an important role in making your bed comfortable and inviting. Pillows can prevent neck pain by keeping your head and spine properly aligned, and your bedding can create a soft and cozy feel while helping to manage your body temperature. Regularly washing your bedding keeps your bed feeling fresh and reduces potential buildup of dust and allergens.
Read Gwern's melatonin page.
Read Lorien Psychiatry's melatonin page.