Many of us are on the losing end of a battle against our biological need for sleep every night. Binging an extra episode. Finishing another level. Working nights. Scrolling on our phones in bed. These decisions are adding up, and they are killing us.
I have always been a big fan of sleep, especially in college. If I wasn’t in class or at work, there was a very good chance I was asleep. But as the years passed, demands on my time grew (whether real or perceived), and flexibility in my schedule quickly fell away.
I now have the average American schedule. Wake, commute, work, commute, relax, sleep. More than any other factor, one thing will determine how I am going to feel the next day. How well and how much I slept. It doesn’t matter how great my workout was or how well I ate. If I didn’t sleep well, I am a moody and unproductive jerk. Since sleep is such a major factor, I am making it the first topic in a series on optimizing health. How does it work? What happens if we don’t get enough? How can we improve it?
“I’ll sleep when I’m dead”. You sure will. And it turns out you’ll get there a lot sooner than everyone else. A growing number of studies show that lack of sleep and poor sleep habits cause lasting negative impacts to our mental and physical health.
When we prevent our bodies from properly restoring themselves, we are not only hurting ourselves, we are increasing risk of accidents that can kill other people. Fatigue and drowsiness contributed to the Three Mile Island accident, Exxon Valdez oil tanker spill, Space Shuttle Challenger disaster, and thousands of automotive deaths every year.
Feel the (Circadian) Rhythm
The first thing I needed to get a better grasp on is the circadian rhythm. My understanding had been limited to a vague notion that sometimes we’re sleepy, sometimes we’re not, and that happens in cycles. I had no idea how important it is to our sleep and health, or why we shouldn’t be fighting that rhythm. Circadian rhythms keep our bodies in sync with the appearance and disappearance of natural light. But how?
When we wake, our eyes are exposed to light. This light hits a special bundle of cells in our retinas which sends a signal to part of our brain called the suprachiasmatic nucleus (SCN). The SCN is another small bundle of cells in our hypothalamus that acts as a station master keeping all the trains on time. It is our internal master circadian clock.
When the SCN gets the retina’s cue that its daytime, it sends signals throughout our bodies to get us primed to take on the day. We experience a rise in body temperature, heart rate, blood pressure, cortisol (the “stress hormone”), ghrelin (the “hunger hormone”), and the delayed release of hormones like melatonin (the “sleep hormone”). When the light fades in the evening, the retinas cue the SCN that it is time to prepare for rest. The SCN sends signals to cool and calm the body, release melatonin, suppress appetite, and reduce stress.
The SCN is like a conductor, keeping our body’s orchestra playing the right parts of the right songs at the right times. It is a carefully crafted masterpiece, tuned through millions of years of evolution. And we’re screwing it all up.
Impact of Light on the Circadian Rhythm
The primary way we are throwing this rhythm out of sync is with an overabundance of artificial light in the evening, and underexposure to bright light during the day. On average, Americans spend 86.9% of the day indoors (20.86 hours), 5.5% in a vehicle (1.32 hours), and 7.6% (1.82 hours). outdoors. This is significantly more time indoors than our pre-industrial ancestors and their complete lack of light bulbs.
Indoors, outdoors, does it matter? Indoor light is still light, after all. Right?
I am writing this in late June from a friend’s beach house, so will use that as an example. On a clear summer day, sunrise and sunset measure at about 400 lux (a measurement of illumination), midday daylight (indirect – in the shade, for example) is about 15,000 lux, and bright, direct sunlight is >100,000 lux. At night, a full moon is about 0.25 lux, and 0.01 lux for a quarter moon. Thousands during the day, and almost none at night.
Compare that to our artificially lit life. Most of our offices and homes are under 500 lux. Many of the devices we stare at well into the night are between 10 – 150 lux. These numbers are way off the mark compared to real daylight and moonlight.
That 20.86 hours of indoor time we mentioned is spent in <500 lux. Assume 8 of those hours are spent asleep. We’ll see in the next section that this is a generous number, but we’re going to roll with it. That means 12.8 of our waking hours are spent in perpetual sunset/twilight levels of light. It is now as if we are living in a dreary winter day all day, every day. And night. Summer is gone.
We’re not getting nearly enough healthy light during the day, and we’re getting way too much light at night. In addition to screwed up circadian rhythms, poor sleep, and increased risk of cancer, this drastic shift in our lighting is causing other issues. These include worsened Seasonal Affective Disorder (S.A.D.) symptoms and lifestyle-induced vitamin D deficiency, which itself is linked to cancer, heart disease, autoimmune diseases, diabetes, and depression.
Health Impacts of Sleep Deprivation and Circadian Rhythm Disruption
The National Sleep Foundation recommends that adults and young adults get 7 – 9 hours of sleep a night. A 2014 Gallup-Healthways Well-Being Index poll finds 42% of Americans get less than 7 hours of sleep a night, and 69% get less than 8.
Lack of sleep and neglect of our circadian rhythms are hurting us in many ways. The already large list of health issues includes cancer, loneliness, heart disease, poor decision making, immune system suppression, diabetes, and obesity. This list continues to grow with each new study.
The list of health consequences is enormous, so I am not going to attempt to go into detail on all of them. Instead, I will dig into one of the ways sleep deprivation and circadian disruption destroys our mind, and one of the ways it destroys our bodies.
Alzheimer’s, dementia, and cognitive decline
Our brain cells are messy workers. During the day they crowd our brain’s pathways like busy street vendors. Quickly responding to multiple orders and tossing aside all their waste products to be dealt with later. Some of this waste, such as Amyloid beta (Aβ), is neurotoxic and builds up in the brain as plaques.
Just 36 hours of sleep deprivation increases Aβ levels by 25% to 30%. Build-ups of Aβ and another protein, tau, appear to work together as the main culprits in Alzheimer’s development. One study refers to Aβ as the trigger and tau as the bullet of the disease. Aβ production is increased with insufficient sleep, and in a vicious cycle, Aβ buildup impairs sleep.
During deep, slow wave sleep, the street vendors seem to pack up their stalls, increasing the space between brain cells by about 60%. This gives plenty of room for the cleaners to come in and hose down the streets. The increased space allows for greater exchange and flow of cerebral spinal fluid and interstitial fluid. This flow flushes away accumulated Aβ and tau, clearing as much as 40% of total Aβ accumulation.
Sleep deprivation means there is less opportunity to clean up our brains, leading to a 68% higher chance of developing Alzheimer’s or other cognitive problems. You may have read that oversleeping may also cause these cognitive impairments, but that doesn’t appear to be the case. Researchers did observe that those regularly sleeping more than 9 hours a night were twice as likely to develop Alzheimer’s. However, since Alzheimer’s, dementia, and other cognitive issues have sleep disturbances as symptoms, those same researchers believe this over-sleeping is an early symptom rather than a contributing factor.
A variety of cancers are also linked to the disruption of our circadian rhythm. We learned that melatonin is regulated by the SCN and circadian rhythm, and that light exposure at night suppresses melatonin. Along with its sleep promotion qualities, melatonin also appears to be pretty great for anti-cancer properties, particularly in conjunction with chemotherapy. More light at night means less melatonin, which seems to mean more cancer.
Studies are showing increased cancer risk in night shift workers (who are frequently studied since they have regular, long-term exposure to light at night) for breast cancer (by 50% – 70%), prostate cancer, colon cancer, endometrial cancer, and others. In addition, there are studies of increased colon cancer among non-night shift workers with sleep deprivation, and increased risk of lung cancer among smoking night shift workers.
There is more work backing the idea that light at night is partially responsible for increased risk of cancer. Studies have shown that those that are totally blind have decreased cancer risk and no melatonin suppression due to light exposure.
Getting Quality Sleep
Take Off and Cruise
This is the beginning of our day. What we do from now until we fall asleep will impact how well we sleep. We are flying planes here, not rockets. The idea is a gradual, gentle climb into our day.
- Wake up at the same time every day. Consistency is important for getting good sleep. Once you’re in a good rhythm you may be able to make a morning alarm a fallback rather than a requirement. Whats great about this is starting the day when your body says it ready, not an alarm.
- Don’t check your phone until you are done with your morning routine. Keep it in Do Not Disturb or airplane mode until you are ready to start your day. Waking up and immediately checking your phone starts your day in a reactive mode.
- Meditation is beneficial at any time of day, so you really can’t go overboard on this one. If you want to meditate in the morning, afternoon, and evening, go for it. Meditating in the morning is a great way to remind yourself how to stay calm and in the present, reducing the stress that compounds throughout the day and limits our ability to sleep.
- Get plenty of bright light exposure. Starting when you wake up, try to find ways to get outdoors and soak up some light. Take walking breaks throughout the morning through afternoon. Move your desk next to a window if you can. Try a light therapy machine if you’re not able to get more natural light during the day.
- Exercise is also great during most of the day, but there are advantages to getting your workout in in the morning, including a 12 hour mood boost. If you do exercise in the evening, keep it light, or at least four hours before bed. This will give your body plenty of time to completely cool off and get back into a restful state. Exercise helps sleep quality and duration, and good sleep helps you exercise. Don’t quit if you don’t see an immediate improvement, though. It can take months to get into a good enough groove to see sleep benefits.
- Get your caffeine in during the first half of the day. It has a half-life of 5-8 hours and a quarter-life of 12 hours, so the later you drink it, the more is in your bloodstream when you are trying to sleep. Caffeine mimics adenosine, which masks fatigue.
Descent and Landing
Time to sleep and get our planes back on the ground. We have two options. 1) Point the nose down and plummet, or 2) a controlled descent. One may seem faster, but the other will leave us feeling a whole hell of a lot better.
- If you drink alcohol, you’ll want to finish your drink about 3 hours before bed. While many people use alcohol to make themselves feel more tired and fall asleep faster, it also makes it more likely you will wake up during the night. Alcohol also reduces your REM sleep, which is important for memory consolidation and learning.
- Your last large meal should also be 3 hours before bed. Evening glucose tolerance is lower than in the morning, something which researchers believe may account for higher diabetes risk of night shift workers. In fact, eating most of your calories in the first half of the day may not just be better for sleep, but your overall weight and metabolic health.
- Create a digital sunset. Turn off screens 1 hour before bed. This helps cut our blue light at night exposure and helps promote melatonin release. Even something as innocent-seeming as a dim e-reader is a problem. One study showed those using e-readers at night had 55% lower melatonin after 5 days. They took longer to fall asleep, had less REM sleep, and felt worse the next day.
- Keep your bedroom cool, dark, and calm. Temperatures between 60 – 68 degrees Fahrenheit (15.5 – 20 Celsius) are best for sleep. Bedrooms should also be as dark and peaceful as possible. Remove as many electronics as you can – the TV definitely needs to go. Blackout curtains and sleep masks are great ways to block out light. Dave Asprey (“The Bulletproof Executive”) has even taped over all the LEDs in his bedroom.
- Take a warm shower 45-90 minutes before bed. When stepping out of the shower, evaporation’s cooling effect lowers your core body temperature. This rapid decline in body temperature seems to be ideal for initiating sleep onset. Studies also show this improves sleep quality, and reduces amount of time required to fall asleep.
- Write down a very specific to do list for the next few days 5 minutes before bedtime. This mental unloading can help you fall asleep faster, possibly by helping clear your mind of things you might otherwise dwell on while trying to fall asleep.
- Go to bed around the same time each night. Again, consistency is key. Dr. Matthew Walker, author of Why We Sleep from University of California’s Center for Human Sleep Science suggests setting a bedtime alarm to help with this if needed. I make use of my Fitbit’s bedtime reminder feature.
- Sleep in a good position. In his online class Maintain Your Body for Long Lasting Health & Mobility, physical therapist and coach Kelly Starrett says to sleep on a soft mattress that gets us out of extension, and with a pillow that keeps our spine in a neutral position. And definitely not on our stomachs.
Online Classes and Learning
I’m a visual learner and a big fan of online video content for learning. These are some of the online classes I have personally used and benefitted from, as well as a circadian-specific genetic report available online.
- Sleep 101 and the many other resources on sleep from Optimize.me
- The Bulletproof Life by Dave Asprey
- Maintain Your Body for Long Lasting Health & Mobility by Kelly Starrett
- If you have 23andme results, you can upload your data to Dr. Rhonda Patrick’s Found My Fitness. This unlocks detailed reports specific to the interaction of your genome and your circadian rhythm.
Additional sources referenced for this post but not directly linked above:
- U.S. Nuclear Regulatory Commission. Investigation into the March 28, 1979 Three Mile Island Accident by the Office of Inspection and Enforcement (Investment Report No. 50-320/j79-10). July, 1979, NTIS NUREG-0600
- Mitler MM, Carskadon MA, Czeisler CA, Dement WC, Dinges DF, Graeber RC. Catastrophes, sleep, and public policy: consensus report. Sleep. 1988;11(1):100–109. doi:10.1093/sleep/11.1.100
- Beta-amyloid and the amyloid hypothesis. Alzheimer’s Association. March 2017.