"...by fixing our sleep problem, Americans can drastically decrease 5 of the top 7 leading causes of death."

By Frank Rosenthal PT, DPT, OCS, CSCS

I want to start off by acknowledging that I am far from perfect when it comes to sleep. Most of us are in this boat, as you will see. Upon learning about some of the new research linking lack of sleep to various diseases, however, I have become passionate about changing my own relationship with catching Z’s, as well as teaching patients about changing theirs.

Sleep Basics

Let’s start with the basic physiology of sleep – what is it and how does it happen? When you think about it, sleeping is pretty strange from an evolutionary perspective- I am going to put down my defenses for a large chunk of time, become unconscious, and be completely helpless against predation?! Viewed from that lens, there must be something incredibly important in sleep that caused evolution to prioritize it (humans spend one third of their entire lives asleep)!

Taking a reductive approach, sleep allows you to reset and grow. Digging a bit deeper though, your brain stays quite active during sleep, tidying up after a day of stimuli bombardment. Sleep affects the brain, heart, lungs, immunity, mood, and disease resistance. It optimizes learning and memory. There is literally no system in the body that it does not impact.

Sleep Stages

You can break down sleep into two main categories – rapid eye movement (REM) sleep and non-REM sleep (3 different stages). As you sleep, your brain cycles through all four stages several times.

  • Stage 1 Non-REM sleep: This is where you transition from being awake to being asleep and it lasts only several minutes. Muscles may occasionally twitch as you relax and the brain slows down a bit. If you’ve ever watched a child fall asleep, you’ll recognize this – breathing slows down and they twitch a little.
  • Stage 2 Non-REM sleep: Light sleep period where your breathing and heart rate continue to slow. Your body temperature drops and eye movements stop. Your brain continues to slow but has intermittent surges of activity. Most of your time sleeping is in this stage.
  • Stage 3 Non-REM sleep: Considered deep sleep, this occurs in longer periods during the first half of the night. Your child or spouse is in this stage when it is really difficult to wake them (per my wife, I must spend a lot of time here). Deep sleep is needed to feel refreshed in the morning, which is accomplished by flushing out certain chemicals (adenosine) from the brain that have accumulated over the course of the day.
  • REM sleep: Characterized by your eyes moving quickly from side to side under your eyelids, this is where most of your dreams happen. Physiologically, it is close to being awake- heart rate and breathing increase, brain wave activity approaches daytime activity. Interestingly, your arm and legs become temporarily “paralyzed”, preventing you from moving along with your dreams (probably a good thing for most married couples). The time spent in REM increases as you go through more cycles. With aging, REM sleep decreases.

Lack of sleep

If you’ve stuck with me thus far, you’re amazing. Before I lose you, let’s go over what happens if we have a lack of sleep.

Some quick, sobering facts:

  • There are 6,000 fatal car crashes each year that can be attributed to drowsy driving (This is not far behind the 10,511 deaths from drunk-driving crashes in 2018)
  • The ideal sleep duration for adults is 8 hours. Americans only log an average of 6.8 hours per night, while 40% of us are sleeping 6 hours or less (raise your hand if you’ve done this)
  • Those who sleep less than 7 hours have nearly 3x the risk of developing Type 2 Diabetes
  • Lack of sleep is not just associated with Alzheimer’s and dementia risk, but has been shown to be causative.

Additionally, you have

  • 50% greater risk of obesity of you sleep less than 5 hours nightly
  • Increased risk for high blood pressure
  • 36% greater risk of colorectal cancer
  • 48% increased risk of heart disease
  • 3x the risk of catching a cold 

Glancing at these stats, an argument can easily be made that by fixing our sleep problem, Americans can drastically decrease 5 of the top 7 leading causes of death: heart disease, cancer, unintentional injuries, Alzheimer’s disease, and diabetes. In 2017, heart disease, cancer, and unintentional injuries (the top 3) made up 68% of deaths from the top 10 leading causes.

Interestingly, when you lose sleep matters as well. If you stay up late, you suffer a decrease in deep sleep. This has the effect of making you feel less refreshed in the morning, altering hormone regulation (weight gain), and increasing your chance of getting sick or feeling depressed. If you go to bed on time, but loose sleep on the back end by getting up too early, you lose REM sleep. This causes memory and concentration problems and slower social and mental processing. You’ll have trouble picking up subtleties of conversation or negotiations.

Yeah, but what does this mean to me?

These stats are nice, but sometimes it helps to look at things from a day-to-day perspective. Here are some ways a lack of sleep can impact your life.

Recovering from pain or surgery

I’ll start with one close to home – how does sleep or lack of sleep affect recovery from an injury or surgery??

Sleep deprivation can up-regulate stress systems and alter immune cell production, leading to overproduction of pro-inflammatory chemicals. This leads to decreased ability to fight off illness and altered tissue healing. Sleep deprivation can slow your recovery process.

It also has effects on pain modulation and perception, cardiovascular health, motor skill learning, cognitive function, learning, and memory – all crucial in the rehab process. Sleep deprivation also increases your risk for falls, accidents, and injuries.

When you’re in pain or post-surgery, sleep disturbance can be especially prevalent, which can contribute to your symptoms and affect your progress.

Trying to maintain a healthy weight

When you chronically have poor sleep, you get more cravings for sweet, salty, and starchy foods

Sleep deprivation leads to higher level of the hunger hormone (Ghrelin) and lower level of  the appetite controlling hormone (Leptin). This is one mechanism that contributes toward weight gain and the development of diabetes

Memory/learning/motor patterns (kids and adults)

Sufficient sleep is crucial for memory and learning. As you sleep, your brain catalogues the previous day, deepens new connections, and optimizes memory storage. People who get sufficient sleep after learning have better recall the following day. Similarly, when you learn a new movement pattern as a child or as an adult (in PT), sufficient sleep allows this pattern to be reinforced and stored for future use.

Easy steps

As you can see, adequate sleep is vital for every aspect of your lift. As you can gather from the number of people who are “under-slept”, improving your relationship with sleep is not easy. However, it is simple. Simple but not easy. Start with these sleep habits and see where they take you.

  • Regularity is key – As much as possible, go to bed at the same time and wake up at the same time every day
  • Avoid light-emitting electronics within at least 30 minutes of trying to sleep
    • These devicies suppress melatonin and keep your brain too active.
  • While you’re thinking about light – completely darken your room – turn off the TV, turn the clock to the wall, and use light-blocking blinds.
  • Cool off! Keep your room around 65- 67degrees, which helps lower your body temperature (something that normally happens as you prepare to sleep).
  • Don’t rely on caffeine or energy drinks
    • Short term help, but throws off natural sleep patterns
  • Alcohol- initially makes you drowsy, but then causes arousal, leading to lack of deep sleep, waking in the night
  • Exercise can help regulate sleep
  • If you are in pain or post -surgery- talk to a PT about body positioning and ways to maximize sleep while in pain.

“I’ll sleep when I’m dead”

I am 100% guilty of using this phrase. I remember the first time – I was on summer break from college, working 4 jobs. One of them entailed closing down a bar at 2am while another began at 7am as a PT tech. Unfortunately, sometimes those two were scheduled back to back. My boss at the PT office asked me how I handled that and my response was “I’ll sleep when I’m dead.” His response (admiration and encouraging words about my great work ethic) as well as my sentiment highlight a deep cultural problem. Sufficient sleep is often seen as a luxury while sleeping less is viewed as a sign of increased productivity. The truth is that sufficient sleep is a necessity both for productivity as well as quality of life and health. It is not a wasteful period of inactivity; rather, it represent active recovery that promotes health, healing, productivity, and creativity.

From the perspective of expanding your life span (how long you live) and health span (how long you stay healthy), getting enough sleep is non-negotiable!

This is the second post in our wellness series. Check out our post about practicing gratitude here.


Matthew Walker’s book “Why We Sleep”

National Institute of Health