When it comes to health and wellness, the two most frequently discussed components are diet and exercise. And although they are crucial contributors, growing science and research is showing that chronic sleep loss has short and long-term consequences on our overall health and wellbeing, and increases our risk for morbidity and mortality.
Sleep Overview
Sleep is a critical time for overall body healing and affects nearly every tissue, organ, and system in our body including the brain, heart, kidneys, and lungs, to blood pressure, metabolism, hormonal and immunological function, mood, disease resistance, and a number of brain functions, including how nerve cells (neurons) communicate with each other.
Even though sleep is a resting state, it actually is an active process of restoration for the brain and body. As Dr. Merrill Mitler, a sleep expert and neuroscientist at the NIH, states,
"Sleep services all aspects of our body in one way or another: molecular, energy balance, as well as intellectual function, alertness, and mood."
The amount of sleep you need will change over the course of your life and may vary from person to person. Most adults require between seven to nine hours of sleep each night. Children and teenagers need substantially more sleep, particularly if they are younger than five years of age. This table reflects recent American Academy of Sleep Medicine (AASM) sleep recommendations that the American Academy of Pediatrics (AAP) has endorsed.
Work schedules, stress, sleep environment, what you eat and drink, medications, and medical conditions, are factors that can prevent us from receiving enough healthy sleep.
According to the National Institue of Health (NIH), sleep deprivation is a condition that occurs if you don't get enough sleep. Sleep debt is the total sleep lost over time (for example, if you lose 2 hours of sleep each night, you'll have a sleep debt of 14 hours after one week). Sleep deficiency is a broader concept and occurs if you have one or more of the following:
You don't get enough sleep (deprivation)
You sleep the wrong time of the day (so you're out of sync with your body's natural clock)
You don't cycle through all the different stages of sleep your body needs
You have a sleep disorder that prevents you from getting enough sleep or causes poor sleep quality (i.e. sleep apnea)
Chronic sleep loss (whether deficiency, deprivation, or debt) is serious and can lead to poor mental and physical health, loss of productivity, safety hazards in the home and workplace, and increases risk of death.
Sleep Stages and Mechanisms
To understand sleep, it helps to understand the different stages of sleep, your biological clock, and circadian rhythms.
The two basic types of sleep are rapid eye movement (REM) and non-REM.
Non-REM sleep includes what is commonly known as deep sleep or slow wave sleep. Dreaming typically occurs during REM sleep. Generally, non-REM and REM sleep occur in a regular pattern of 4–5 cycles each night. According to Dr. Michael Twery, a sleep expert at NIH,
"As the night goes on, the portion of the cycle that is REM sleep increases. It turns out that this pattern of cycling and progression is critical to the biology of sleep."
You have an internal "body clock" that controls when you're awake and when your body is ready for sleep. This clock typically follows a 24-hour day-night cycle - called the circadian rhythm.
Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Circadian rhythms play a vital role in virtually all systems of the body and how they function, including the sleep-wake cycle, hormone secretion, blood pressure, metabolism, hunger, body temperature, mood, and fluid balance.
Circadian rhythms regulate the production of different hormones throughout the 24-hour cycle. When the sun rises in the morning, the body produces cortisol, a hormone that makes us feel refreshed and alert. After waking, a healthy person will become increasingly tired throughout the day until the sun goes down, then feelings of tiredness peak. As the sun starts to set, the pineal gland will release melatonin, a hormone that reduces wakefulness and alertness.
The circadian rhythms throughout the body are connected to a master clock located in a part of the brain called the suprachiasmatic nucleus (SCN), which is found in the hypothalamus. At different times of the day, clock genes in the SCN send signals to regulate activity through the body.
The SCN is extremely sensitive to light, which serves as an external cue that influences signals sent by the SCN to coordinate internal clocks in the body. For this reason, the sleep-wake cycle is one of the most prominent circadian rhythms.
Over time, circadian rhythms are influenced by behavioral patterns and external stimuli. Our biological clock's control centers are regulated by energy balance, feeding and fasting, temperature, physical activity, as well as light and darkness. The clocks can be affected and confused by a variety of things such as mutations or changes in certain genes, jet lag or shift work interrupting the light-dark cycles, and the lights emitted from electronic devices at night.
Every change in the biological rhythm affects the communication between cells and tissues, resulting in their gradual deregulation. This deregulation is what leads to a variety of chronic health problems, poor mental health, and impacts performance and safety.
Sleep and Physical Health
While you sleep, your body is repairing and processes are working. Insufficient sleep is linked to an increased risk of heart disease, kidney disease, stroke, high blood pressure, obesity, type 2 diabetes, and impaired growth and development.
Researchers found when internal biological clocks are out of sync with external rhythm regulators (i.e. light/dark), the heart becomes damaged and enlarged (cardiomyopathy) and the kidney tubules sustain significant scarring. This damage and scarring can lead to heart and kidney disease. Researchers from the National Kidney Foundation have also discovered the impact of sleep-wake cycle on kidneys' workload and the outcomes for those that have kidney disease. Dr. McMullan, head of the research states,
"Nocturnal patterns can affect chronic kidney disease and people who sleep less usually have faster kidney function decline."
Sleep deficiency also increases the risk of obesity. For example, one study of older adults (ages 51-72 years) who slept less than 7-8 hours increased their chance of obesity by 40%. Another study from the University of California, Berkley, and Columbia University linked sleep and body mass index. The researchers looked at more than 3,300 teenagers over a 15 year period, and the research showed that with each hour of sleep lost, the odds of becoming obese went up (2.1 point increase in BMI over a 5 year period). Additionally, one of the largest studies performed to date, the Nurses' Health Study, followed 68,000 women for 16 years, found those who slept less than five hours per night were 30% more likely to gain 30 pounds compared to those who slept for seven hours per night.
Sleep helps maintain a healthy balance of the hormones that make you feel hungry (ghrelin) and full (leptin). When you don't get enough sleep, your level of ghrelin goes up and your level of leptin goes down. This makes you feel hungrier than when you're well-rested, which can lead to overeating and weight gain (also increasing the risk of obesity).
Sleep also affects how your body reacts to insulin, the hormone that controls your blood glucose (sugar) level. Sleep deficiency results in a higher than normal blood sugar level, which may increase your risk for type 2 diabetes.
Furthermore, sleep supports healthy growth and development. Deep sleep triggers the body to release growth hormone (GH), the hormone that promotes normal growth in children and teens. This hormone also boosts muscle mass and helps repair cells and tissues in children, teens, and adults. Sleep also has an impact on puberty and fertility due to functions within the brain and the circadian control on our hormones.
Your immune system relies on sleep to stay healthy. This system defends your body against foreign or harmful invaders. Ongoing sleep deficiency can change the way in which your immune system responds by producing less cytokines (proteins that help fight infections and inflammation). Studies support the view that sleep is particularly important for initiating effective adaptive immune responses that eventually produce "long-lasting immunological memory"(meaning it enables our bodies to respond more rapidly and more effectively to a second challenge by the same pathogen.)
Sleep and Healthy Brain Function and Emotional Well-Being
Your central nervous system (CNS) is the main information highway of your body and is composed of the brain and spinal cord. Sleep is necessary to keep the CNS functioning properly and chronic sleep loss can disrupt how your body usually sends and processes information.
Neurons (nerve cells) are the fundamental units of your brain and nervous system and the cells are responsible for receiving sensory input from the external world, sending motor commands to our muscles, and for modifying and relaying the electrical signals every step in between.
Sleep impacts how neurons communicate with each other and aids to form new pathways between neurons which enable you to learn and remember information. Without sleep, your brain is exhausted, so your cognitive and emotional abilities become disrupted and the brain can't perform its duties as well.
Sleep is one of our body's functions designed to purge the brain of built up wastes through the glymphatic system. In simpler terms, sleep "clears out the daily clutter" of the brain. This disposal process includes getting rid of proteins from the CNS that form plaque around the brain and can lead to neurodegenerative disorders such as Alzheimer's disease, the most common cause of dementia. This plaque, called beta-amyloid, is a toxin substance that accumulates in the brain and research has shown it to be inversely related to sleep (when sleep increases, the plaque decreases).
Sleep deprivation also negatively affects our emotional state. Without sleep we may feel more impatient, prone to mood swings, and have higher levels of agitation and frustration. These swings in our emotional state can lead to problems with communication and have a negative impact on our personal and professional relationships.
If sleep deprivation continues long enough, you could start having hallucinations (seeing or hearing things that aren't there.) For example, a systematic review was conducted on 476 studies. Of these, 21 studies were eligible for review. All studies, except one reported perceptual changes, including visual distortions, illusions, and hallucinations with a duration of sleep loss ranged between 24 hours and 11 nights. Authors claimed that participants resembled that of "acute psychosis or toxic delirium." A period of normal sleep resolved psychotic symptoms in many of the participants.
A lack of sleep can also trigger mania in people who have bipolar mood disorder. Other psychological risks include impulsive behavior, anxiety, depression, paranoia, and suicidal thoughts. Additionally, some research suggests, there is a "bidirectional relationship between sleep and mental health" in which sleeping problems may be both a cause and consequence of mental health problems.
David Gozal, MD, a sleep researcher at the University of Chicago claims we treat sleep like a "tradable commodity," sacrificing it for work, entertainment, or another lifestyle choice. In the meantime he believes, everything from our health to our relationships to our "sense of wonder" gets diminished. Gozal says,
"Sleep is the food of the brain." He believes that many of us aren't just hungry for sleep, "We are starving."
Sleep and Performance and Safety
Getting enough sleep at the right times helps you function well throughout the day. People who are sleep deficient are less productive at work and school, take longer to finish tasks, have slower reaction time, and make more mistakes.
For example, a study conducted by researchers at the University of Texas in Austin split West Point cadets into two groups. Half of the cadets were sleep deprived, and the other half were well rested. All study particaipants performed the tasks twice, separated by a 24-hour period. Cadets who were sleep-deprived between testing periods saw their accuracy decline by 2.4 percent, and cadets who were well-rested between testing periods improved by 4.3 percent.
Not everyone is aware of the risk of sleep deficiency. In fact, many may not realize they are sleep deficient. Even with limited or poor quality sleep, they may still think they can function well.
For example, drowsy drivers may feel capable of driving. Yet, studies show that sleep deficiency harms your driving ability as much as, or more than, being drunk. A study by the AAA Foundation for Traffic Safety estimated that 328,000 drowsy driving crashes occur annually. The same study found that 109,000 of those drowsy driving crashes resulted in an injury and about 6,400 deaths.
Drivers aren't the only ones affected by sleep deficiency. It can affect people in all lines of work, including health care workers, pilots, students, lawyers, mechanics, and assembly line workers. Thus sleep deficiency is not only harmful on a personal level, but it also can cause large-scale damage.
Some of the most monumental disasters of history such as Exxon Valdez oil spill, Chernobyl disaster (power plant explosion), Three Mile Island (near meltdown of nuclear plant reactor), and the Challenger explosion have direct links to drowsiness, fatigue, and sleep deprivation.
James Maas, PhD, a recently retired Cornell scientist and one of the world's leader's in sleep researcher, states,
"As a society we are so habituated to low levels of sleep that most of us don't know what it feels like to be fully alert and awake."
Improving Sleep Health
Paying attention to good sleep hygiene is the first thing you can do to set yourself up for better sleep. Having strong sleep hygiene means implementing lifestyle behaviors and sleep habits to foster healthy sleep each night. There are some tips below, but remember the basic concept of sleep hygiene is that your habits and environment are optimized for sleep, but what "ideal" sleep looks like can vary from person to person, so you may need to test different practices and make adjustments accordingly.
Follow a sleep schedule: Varying your bedtime or morning wake-time can hinder your body's ability to adjust to a stable circadian rhythm.
Create a restful environment and primed for sleep: Quiet, dark, and relaxing bedrooms are more appealing to sleep in! Heavy curtains, ear plugs, blackout shades, and sleep masks are some tools that can be used to improve your sleep environment.
Get exercise: Activity during the day can support your internal clock and help make it easier to fall asleep at night.
Find the sun: Exposure to natural light, especially early in the day, helps reinforce your strongest circadian cue.
Watch your caffeine and alcohol: Stimulants like caffeine can keep you awake and throw off the natural balance between the sleep-wake cycle. Everyone is different, but if you're having trouble sleeping, you should avoid caffeine after noon. Keep in mind caffeine has a half-life of about 5 hours. So if you consume 95 milligrams (mg) of caffeine (the amount in a 8 ounce cup of coffee), after 5 hours, you'll still have about 45 mg in your body! If you metabolize caffeine slowly (like me) you'll have more in your system after 5 hours (so you may need to have an earlier cut off time). Alcohol is a sedative that causes your brain activity to slow down, so it can induce feelings of relaxation and sleepiness, but consuming in excess has been linked to poor sleep quality and duration.
Limit light before bed: Artificial light exposure (at night) can interfere with circadian rhythms. Try dimming the lights and stepping away from the electronic devices well before bed time (such as an hour or two). If you need (or want) to be in front of your electronic devices, then consider buying a pair of blue blockers. They work wonders for reducing eye strain and filtering out artificial light.
Keep naps short and earlier in the day: If you nap, keep it short and earlier in the afternoon so it doesn't throw off your sleep schedule at night.
Eat your last meal a few hours before bed: When you sleep your body is in a "rest and digest" state. The core temperature comes down, your eye movements stop, and your heart rate and muscles continue to relax. A large meal can signal wakefulness and has a higher thermal effect, so it increases the core temperature of your body, which can interfere with sleep by disrupting the circadian rhythm. However, going to bed hungry can be counterproductive as well, so having a small, protein-dense snack may be beneficial if you're hungry.
Track your Sleep: Tracking sleep through smart technology such as apps and wearable items (i.e. bracelets, smart watches, rings, and headbands) allows you to collect and analyze applicable data about your sleep to help tackle sleep problems. Depending on the device, you can measure your total amount of sleep, sleep disturbances and time spent awake, how long it takes to fall asleep, time in sleep phases/cycles, as well as monitor your heart beat and respiration. Using a companion app, you can sync the data from some sleep devices to a smartphone or tablet, or uploaded to a PC.
Manage stress: Although impossible to avoid stress completely, there are daily practices you can implement to help mitigate stress. Nasal breathing, meditation, walks outside, reading a book, exercise, and gratitude journals are a few examples of rituals that have been shown to help control stress and worries.
If you haven't been sleeping well for a while, be patient with yourself because depending on the reason, it may take time to get back on track. With everything going on in the world right now, it can be extra challenging to keep stress levels down - I get it!
If you feel like you've been trying for a while to get healthy sleep and nothing is working, then talk with your doctor about it. There may be something medically that needs to be addressed and your doctor may recommend a sleep test (which is covered by most insurances after your deductible is paid).
Keep in mind if your always frustrated and stressed about not sleeping, then that could hinder your sleep and prevent you from getting back on track. In the meantime, set your environment up for sleep success and commit to making a sleep a priority.
Please let me know if you already use specific practices to get a good night's sleep! I am interested to know what works for you! Also, please feel free to reach out if you need help with any barriers you're facing catching your zzzz's.
Until next time, stay well!