The book I read this week is “Why We Sleep” by Matthew Walker, an English scientist, and professor of neuroscience and psychology at the University of California, Berkeley.
As a former military officer, I still remember the long periods of sleep deprivation and the “visible” short-term effects on me and others, but after reading this book, I am now scared about a lot of incredible devastating effects taking place when someone doesn’t sleep enough. I started studying the topic by following a MOOC (I think everyone must know what a MOOC is), the great course “Sleep Deprivation: Habits, Solutions, and Strategies” provided by the University of Michigan, but I found out that Walker’s book was suggested also by a lot of notable smart people (e.g., you can find it on Bill Gates’ notes).
“Routinely sleeping less than six or seven hours a night demolishes your immune system, more than doubling your risk of cancer. Insufficient sleep is a key lifestyle factor determining whether or not you will develop Alzheimer’s disease. Inadequate sleep—even moderate reductions for just one week—disrupts blood sugar levels so profoundly that you would be classified as pre-diabetic. Short sleeping increases the likelihood of your coronary arteries becoming blocked and brittle, setting you on a path toward cardiovascular disease, stroke, and congestive heart failure.”.
Lack of sleep contributes to all major psychiatric conditions (e.g. depression, anxiety, suicidality), it increases the hormone of hungry feeling while suppressing the hormone that signals food satisfaction, so leading to obesity and overweight.
Yes, I think everyone should read this book. Schools and Universities teach a lot of stuff, sometimes really useless and/or outdated, I really cannot find a reason why professors don’t spend a little time to inform about sleep. But you here can find an easy recap about the reasons why we sleep, the effects in case you try to reduce/avoid it, and practical solutions.
Please note that the following work is only intended to be used for educational purposes, under fair use. I recommend you to buy the book, it’s really worth it.
To Sleep
For the reasons written above, it’s clear to scientists: the shorter your sleep, the shorter your life span, not to mention deadly circumstance when driving (extreme case in a rare disorder: 12 to 18 months of no sleep, the patient will die).
World Health Organization (WHO) has now declared a sleep loss epidemic throughout industrialized nations.
Every species studied to date sleeps. Dreaming provides a unique suite of benefits to all species. Consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity.
Yes, a balanced diet and exercise are important, but sleep is more important.
Caffeine, Jet Lag, and Melatonin
2 factors influence mind and body:
- A day-night rhytm signal from internal 24h clock (deep within the brain);
- A chemical substance that builds up in your brain and creates a “sleep pressure.”
Everyone generates a circadian rhythm (“circa” = “around” + “dian” (from diam) = “day”).
Light of the sun methodically resets our inaccurate internal timepiece each and every day, but other Zeitgeber (“time giver”) signals can be used in addition to (or absence of) daylight.
24h biological clock sitting in the middle of your brain is called the suprachiasmatic nucleus. (supra = above + chiasm = crossing point). The crossing point of optic nerves comes from your eyeballs (switch sides). It “samples” the light signal being sent from each eye to reset its inherent time inaccuracy to a crisp twenty-four-hour cycle, preventing any drift.
Not everyone approaches sleep the same way:
“Morning types” (40% of the population) prefer to wake at or around dawn and function optimally at this time of day. Others are “evening types” (30% of the population) that prefer going to bed late and subsequently wake up late the following day. The remaining 30% of people lie somewhere in between morning and evening types, with a slight leaning toward eveningness. An adult’s owlness or larkness, also known as their chronotype, is strongly determined by genetics.
Unlike morning larks, night owls are frequently incapable of falling asleep early at night, no matter how hard they try. It is only in the early-morning hours that owls can drift off, so owls are more chronically sleep-deprived, having to wake up with the larks, but not being able to fall asleep until far later in the evening.
One of the biological-historical possible reasons for the different chronotypes: the night owls in the group would sleep 1 to 9 a.m. while the morning larks would sleep 9 p.m. to 5 a.m. Consequently, the group as a whole is only collectively vulnerable (i.e., every person asleep) for just four rather than eight hours, despite everyone still getting the chance for eight hours of sleep. That’s potentially a 50 percent increase in survival fitness:
Melatonin (a.k.a. “the hormone of darkness“) is the circulating messenger used by the suprachiasmatic nucleus to communicate its repeating signal of night and day to your brain and body.
Jet planes speed through time zones faster than our 24h internal clocks could ever keep up with or adjust to: we feel tired and sleepy during the day in a distant time zone because our internal clock still thinks it is nighttime.
It feels harder to acclimate to a new time zone when traveling eastward than when flying westward:
– the eastward direction requires that you fall asleep earlier than you would normally, which is a tall biological order for the mind to simply will into action. In contrast, the westward direction requires you to stay up later, which is a consciously and pragmatically easier prospect.
– when shut off from any outside world influences, our natural circadian rhythm is innately longer than one day (about 24h 15min).
Scientists have studied airplane cabin crews who frequently fly on long-haul routes and have little chance to recover:
– parts of their brains (specifically those related to learning and memory) had physically shrunk, suggesting the destruction of brain cells caused by the biological stress of time-zone travel;
– their short-term memory was significantly impaired.
Other studies of pilots, cabin crew members, and shift workers have reported additionally disquieting consequences, including far higher rates of cancer and type 2 diabetes than the general population (and controlled match individuals who do not travel as much).
The 2nd factor determining wake and sleep is sleep pressure: while you’re reading this, a chemical called adenosine is building up in your brain. It will continue to increase in concentration with every waking minute that elapses.
You can, however, artificially mute the sleep signal of adenosine by using a chemical that makes you feel more alert and awake: caffeine – it’s not a food supplement but the most widely (ab)used psychoactive stimulant in the world (the 2nd most traded commodity on the planet, after oil). The consumption of caffeine represents one of the longest and largest unsupervised drug studies ever conducted on the human race, perhaps rivaled only by alcohol, and it continues to this day. Caffeine blocks and effectively inactivates the receptors, acting as a masking agent. Levels of circulating caffeine peak approximately 30 minutes after oral administration and its persistence (in pharmacology, we use the term “half-life”, referring to the length of time it takes for the body to remove 50% of a drug’s concentration) is five to seven hours.
Caffeine (in coffee, certain teas, and many energy drinks, but also foods such as dark chocolate and ice cream, as well as drugs such as weight-loss pills and pain relievers) keeps people from falling asleep easily and sleeping soundly thereafter, typically masquerading as insomnia, an actual medical condition. Also, be aware that de-caffeinated does not mean non-caffeinated (15 to 30% of the dose of a regular cup of coffee). Caffeine is removed from your system by an enzyme within your liver that gradually degrades it over time. It depends on genetics and age (the older, the worse). Note: once the caffeine effect disappears, you are hit with the sleepiness you had experienced two or three hours ago before you drank that cup coffee plus all the extra adenosine that has accumulated in the hours in between, impatiently waiting for caffeine to leave.
Coming back to adenosine: it creates a pressure to sleep, also known as Process-S. Across the night, sleep lifts the heavy weight of sleep pressure, lightening the adenosine load. After approximately eight hours of healthy sleep in an adult, the adenosine purge is complete. While the process is ending, the energizing circadian activity rhythm has returned.
Now, listen to your body: after waking up in the morning, could you fall back asleep at 11 a.m.? If so, you are likely not getting sufficient sleep quantity and/or quality. Can you function optimally without caffeine before noon? If not, then you are most likely self-medicating your state of chronic sleep deprivation. When you don’t get enough sleep, one consequence among many is that adenosine concentrations remain too high. Like an outstanding debt on a loan, come the morning, some quantity of yesterday’s adenosine remains. You then carry that outstanding sleepiness balance throughout the following day. Also like a loan in arrears, this sleep debt will continue to accumulate. Please take 5 minutes to answer these simple questions (SATED questionnaire):
Tips for Getting a GoodNight’s Sleep
Following, 12 recommendations published by the National Institutes of Health on MedlinePlus magazine, summer 2012.
1. Stick to a sleep schedule
Go to bed and wake up at the same time each day. As creatures of habit, people have a hard time adjusting to changes in sleep patterns. Sleeping in at the weekend won’t fully make up for a lack of sleep during the week and will make it harder to wake up early on Monday morning. Set an alarm for bedtime. Often we set an alarm for when it’s time to wake up but fail to do so for when it’s time to go to sleep. If there is only one piece of advice you remember and take from these twelve tips, this should be it.
2. Exercise is great, but not too late in the day
Try to exercise at least thirty minutes on most days but not later than two to three hours before your bedtime.
3. Avoid caffeine and nicotine
Coffee, colas, certain teas, and chocolate contain the stimulant caffeine, and its effects can take as long as eight hours to wear off fully. Therefore, a cup of coffee in the late afternoon can make it hard for you to fall asleep at night. Nicotine is also a stimulant, often causing smokers to sleep only very lightly. In addition, smokers often wake up too early in the morning because of nicotine withdrawal.
4. Avoid alcoholic drinks before bed
Having a nightcap or alcoholic beverage before sleep may help you relax, but heavy use robs you of REM sleep, keeping you in the lighter stages of sleep. Heavy alcohol ingestion also may contribute to impairment in breathing at night. You also tend to wake up in the middle of the night when the effects of the alcohol have worn off.
5. Avoid large meals and beverages late at night
A light snack is okay, but a large meal can cause indigestion, which interferes with sleep. Drinking too many fluids at night can cause frequent awakenings to urinate.
6. If possible, avoid medicines that delay or disrupt your sleep
Some commonly prescribed heart, blood pressure, or asthma medications, as well as some over-the-counter and herbal remedies for coughs, colds, or allergies, can disrupt sleep patterns. If you have trouble sleeping, talk to your healthcare provider or pharmacist to see whether any drugs you’re taking might be contributing to your insomnia and ask whether they can be taken at other times during the day or early in the evening.
7. Don’t take naps after 3 p.m.
Naps can help make up for lost sleep, but late afternoon naps can make it harder to fall asleep at night.
8. Relax before bed
Don’t overschedule your day so that no time is left for unwinding. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.
9. Take a hot bath before bed
The drop in body temperature after getting out of the bath may help you feel sleepy, and the bath can help you relax and slow down so you’re more ready to sleep.
10. Dark bedroom, cool bedroom, gadget-free bedroom
Get rid of anything in your bedroom that might distract you from sleep, such as noises, bright lights, an uncomfortable bed, or warm temperatures. You sleep better if the temperature in the room is kept on the cool side. A TV, cell phone, or computer in the bedroom can be a distraction and deprive you of needed sleep. Having a comfortable mattress and pillow can help promote a good night’s sleep. Individuals who have insomnia often watch the clock. Turn the clock’s face out of view so you don’t worry about the time while trying to fall asleep.
11. Have the right sunlight exposure
Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least thirty minutes each day. If possible, wake up with the sun or use very bright lights in the morning. Sleep experts recommend that, if you have problems falling asleep, you should get an hour of exposure to morning sunlight and turn down the lights before bedtime.
12. Don’t lie in bed awake
If you find yourself still awake after staying in bed for more than twenty minutes or if you are starting to feel anxious or worried, get up and do some relaxing activity until you feel sleepy. The anxiety of not being able to sleep can make it harder to fall asleep.
