THE CONSEQUENCES OF SLEEP DEPRIVATION
We’re chronically sleep-deprived in the U.S.
Only 42% of adults are getting the recommended seven hours of sleep a night, and as many as 70 million Americans currently have a sleep disorder like insomnia or sleep apnea. 37.9% have fallen asleep unintentionally in the last month, and a shocking 4.7% of people report falling asleep at the wheel. In fact, sleep deprivation is thought to be responsible for 1500 road traffic accident deaths every year.
What is sleep deprivation?
The most basic definition of sleep deprivation is getting fewer than seven hours per night. Most of us will do this occasionally and will quickly recover when we return to normal sleeping patterns with few ill effects. However, when this happens over an extended period, sleep deprivation becomes chronic, and the health implications are serious.
We now know that quality matters just as much as quantity. It’s important not just to get seven hours of sleep a night, but to spend as much of that time as possible in deep, restorative sleep. If you’re not spending enough time in this stage, you’ll experience the health effects of sleep deprivation regardless of how long you sleep.
Why does sleep deprivation happen?
One of the main causes of sleep deprivation is circadian rhythm disturbance.
Inmy previous article, I explained that your daily sleep/wake cycle, or circadian rhythm, is controlled by your circadian clock, which takes its cues from daylight.
Our ancestors didn’t have clocks to tell them when to wake up and when to go to sleep. Their circadian clocks were naturally synchronized to the sun, meaning they would start to get sleepy at sunset, and they’d start to feel alert and awake again at sunrise.
Every single cell in our bodies has evolved to function optimally on this day/night schedule. However, modern life has thrown it completely out of balance.
We’re woken up by alarm clocks instead of the sun. We work all day in artificially lit offices with very little real sunlight. Then we get home at sunset, sit in our bright lounges, and stare at our blue-light-emitting devices late in to the night.
Or we work shift patterns, spending all day in bed and all night in an artificially lit room. And then just as we’re starting to adjust, the schedule changes.
Can’t you catch up on missed sleep?
Not exactly. There’s a common misconception that you can make up for lost sleep on another night, or with a weekend sleep-in.
Unfortunately, while the extra rest may make you feel a little better, you’ve still missed out on vital cycles of sleep on those shorter nights. The negative effects begin immediately and add up over time, eventually leading to serious health issues.
The consequences of sleep deprivation
Stress is both a cause and a consequence of chronic sleep deprivation. The more stressed you are, the harder it is to fall asleep (and stay asleep). The less sleep you get, the harder you find it to cope with stress, eventually locking you in a vicious cycle.
This happens because of cortisol, the hormone at the center of both your stress response and your sleep/wake cycle. When you’re stressed, your cortisol levels stay high well into the evening, when they should be naturally dropping and making way for the sleep hormone melatonin.
The result is that instead of feeling sleepy as the evening goes on, you remain on “high alert”. You find it harder to fall asleep and when you do, it’s a light sleep instead of the deep, restorative sleep you need for good health.
If you’re chronically stressed, your cortisol response will be permanently “switched on”. You’ll start to feel mentally and physically drained, which will cause you even more stress.
Your gastrointestinal (GI) system is one of the most complex in your body, and its own circadian rhythm is closely tied to your sleep/wake cycle.
As your cortisol rises in the morning, it triggers the release of the hunger hormone, ghrelin, and kicks your metabolism and digestive system into action.
Throughout the day, your GI system oversees the secretion of stomach acid, bile and enzymes to help you digest your food. It’s also responsible for moving the food through your GI tract, extracting nutrients, and regulating the function of your gut bacteria.
In the evening, as cortisol levels fall, melatonin levels rise and you start to feel sleepy. Your appetite starts to subside, your metabolism slows down, and your digestive system goes into “rest and recover” mode.
With so many essential roles in the body, even a small disruption to your GI cycle can cause wide-ranging problems.
For example, if you eat late at night, you keep your digestive system active into the early hours, along with organs like the liver. Because you’re depriving your digestive system of the chance to recuperate, you’re likely to experience symptoms like bloating, indigestion, constipation and diarrhea.
You won’t be able to break down your food and absorb nutrients efficiently, which will leave you feeling tired and sluggish. Your body will interpret this as an urgent need to eat, and you’ll find yourself craving energy-dense foods that can cause you to gain weight.
Extended sleep deprivation can lead to a chronic desychronization of your GI and sleep/wake cycles. When this happens, you’re at risk of gastrointestinal disorders like irritable bowel syndrome, gastroesophageal reflux disease, leaky gut, peptic ulcers, and even colon cancer.
As well as leaving you too tired to make healthy food choices, chronic sleep deprivation can affect your weight by disrupting the function of several key hormones.
The first is insulin, which is released after you eat in order to transport glucose from your blood into your cells. It does this by preventing your body from burning fat and forcing it to focus on glucose instead.
When your cells have enough glucose, any extra is stored as glycogen in the liver, and then as body fat. When this happens regularly, you’ll start to gain weight. This often occurs due to persistent overeating, but it can also happen due to lack of sleep.
Your insulin rhythm is closely linked to your sleep/wake rhythm. During the day, when you’re awake and using energy, your cells are more sensitive to insulin. At night, when you’re sleeping, your cells become more resistant.
If you stay up late, you’re likely to eat more food than usual, at a time when your cells are most resistant to insulin. That means you can’t use the glucose for energy, which triggers the release of ghrelin, the hunger hormone, and suppresses leptin, the hormone that makes you feel full.
You end up feeling hungrier, craving energy-rich foods, and finding it difficult to satisfy your appetite — a recipe for weight gain. And since insulin inhibits fat-burning, you’ll also find it very difficult to lose that excess weight.
Insulin resistance and type 2 diabetes
Night-time insulin resistance is normal, but if you’re always tired and frequently overeating, insulin resistance can become chronic.
When your cells fail to take in glucose, your pancreas releases more insulin, which makes your cells even more resistant. Eventually, this cycle causes the insulin-producing beta cells in your pancreas to “burn out” and your blood glucose levels become dangerously high.
This is known as type 2 diabetes, a chronic disease associated with obesity, strokes, blindness, heart disease, amputation, stroke, and premature death.
The liver has its own circadian rhythm, cycling through a number of essential functions throughout the 24-hour day.
During the daytime, your liver helps to digest and metabolize food, use and/or store energy, and keep blood sugar stable. At night, your liver creates essential proteins and detoxifies your body.
If you stay up late or you don’t get enough quality sleep, your liver can’t perform these nightly functions properly. And because of the liver’s vital role in digestion and metabolism, eating before bedtime prevents your liver from entering this detox phase altogether.
If your liver’s circadian rhythm becomes chronically disrupted by bad sleep habits, you can eventually experience health problems like slow metabolism, diabetes, fatty liver disease, excessive or impaired bile production, and liver cancer.
Your cardiovascular system is designed to be most efficient during the day when you’re active, slowing down at night. If you’re not getting enough sleep, your heart is forced to keep working at peak output without sufficient rest, which eventually takes a huge toll.
Just one night of poor sleep is enough to raise your blood pressure over the following 24 hours. Over time, this can cause chronic high blood pressure, a major risk factor for cardiovascular disease.
Sleep deprivation is also strongly linked to stroke, heart attacks, irregular heartbeat, coronary heart disease, and premature death. The more sleep-deprived you are, the higher the risk, especially if you have a sleep disorder like sleep apnea.
During the day, your immune system releases key proteins, cells and antibodies to help you fight off infection. At night, when the threat is lower, these are replenished ready for the next day.
Sleep deprivation makes it difficult for your immune system to recognize foreign DNA and reduces its ability to regulate vital cell and hormone production. Not only does this increase your risk of getting sick, it also triggers a huge inflammatory response.
Inflammation is a necessary part of your immune response, but your body is only designed to tolerate small amounts. When inflammation becomes excessive or chronic — through persistent sleep deprivation, for example — it can start to cause serious illness.
Chronic inflammation can damage your vascular system, harden your arteries, and increase your risk of heart disease. It’s also linked to premature ageing, Alzheimer’s and dementia, as well as painful conditions like fibromyalgia.
In some cases, inflammation can cause your immune system to attack your own tissues, leading to painful autoimmune disorders like rheumatoid arthritis, type 1 diabetes, and inflammatory bowel disease.
Your mental health and mood are influenced by a number of hormones and neurotransmitters, including cortisol, serotonin and dopamine. They all interact with each other throughout the day, but if your sleep/wake cycle is disrupted, they can be thrown out of balance.
Cortisol keeps you alert, but when your cortisol levels are persistently high thanks to sleep deprivation, alertness can quickly become anxiety. Poor sleep also means low melatonin, which affects serotonin function and can cause depression. And when dopamine function is impaired, your risk of addiction soars.
During a normal 24-hour day, your muscles supply your body with energy throughout the daytime, and then focus on resting and repairing while you sleep. When you don’t get enough quality sleep, your muscles don’t get the vital healing time they need. You end up feeling weak and fatigued, and it takes you much longer to recover from exercise.
Throughout the day, your brain is busy taking in your surroundings, decoding sensory input, directing activity around the body, and staying alert for threats. Sleep is when your brain slows down, processes the day’s events, and consolidates information your memory. It also gives your brain the chance to “clean up” the neurotoxins that have accumulated throughout the day.
Your brain needs deep, quality sleep to carry out these functions. You’ll start to see the cognitive effects of sleep deprivation immediately, as you’ll know if you’ve ever experienced “brain fog” after a sleepless night.
If you’re not getting enough sleep, you’ll struggle to concentrate, retain information, recall memories, or perform basic cognitive tasks. If your sleep deprivation is chronic, your risk of degenerative diseases like Alzheimer’s increases significantly.
Human Growth Hormone, or HGH, is a powerful chemical responsible for growth, cell reproduction, cell regeneration, building muscle, repairing tissue, healing injuries, and many more essential functions.
Because melatonin stimulates HGH production, levels are highest during the night. However, if you suppress melatonin function by staying up late, watching TV or using devices, for example, you’ll also deprive yourself of HGH. This can lead to slow healing, fatigue, mental illness, osteoporosis, loss of muscle mass, slow metabolism, and cognitive dysfunction.
It’s not all bad news…
We all know that we should be getting more sleep, but many people don’t realize just how dangerous missing out on sleep can be. There’s good news, though!
With just a few small lifestyle changes and some healthier habits, you can dramatically improve your sleep — and your health.