"Why do we sleep?" is a question you've probably asked yourself at some point in your life. Heck, I know I certainly have. So let's break it down...
Well, simply put ... your body needs sleep! I really can't stress that enough. Sleep allows your brain and body to recharge and restore energy lost during the day. Sleep also helps the body fight off illness, diseases, and nasty bugs.
On top of that though, sleep is especially crucial for your brain. Without it, your brain can struggle to concentrate, process information, and store memories.
The importance of sleep to the body and brain is backed by plenty of research too. Really, the reason it's so important is because it gives your brain and body uninterrupted time to perform essential functions.1
In fact, this statistic may surprise you — people who got optimal sleep every night compared to those who didn't had a 74% lower risk for cardiovascular conditions!2
Given the enormous impact sleep can have on your body ... it’s no surprise that one study found that sleep-deprived people were not only less healthy, but less attractive too.3
Since sleep is so important, I wanted to compile these studies in one place for you. Keep reading to find the answers to over a dozen of the most popular questions about sleep...
How Long is A Sleep Cycle?
Sleep and the pattern of your body’s sleep cycle is not consistent over the course of the whole night. Instead, your body has several rounds of sleep cycles.
These cycles typically range from 90 to 120 minutes4 in length. The first sleep cycle begins about 60 to 90 minutes after you fall asleep5 and lasts about 70-100 minutes. Surprisingly, the first sleep cycle is the shortest, as later cycles will vary between 90 to 120 minutes in length.6
One of the most crucial parts of the sleep cycle is the fourth stage: Rapid Eye Movement (REM). Believe it or not, REM sleep is reported to be 20 to 25% of the total sleeping period!
REM sleep is also where we have the most vivid and bizarre dreams, emotional processing, and where healthy brain development occurs. Adults normally spend about 20% of their sleep in the REM stage, while babies spend about 50% of the time at this stage.7
How Much Sleep Do I Need?
So ... how much sleep do you really need? To some extent, it depends on the person. Here are some quick facts that can help you decide how much sleep you need.
Let’s start with adolescents ... did you know that teenagers who get fewer than eight hours of sleep have increased risk of obesity?8 In one study, adolescents who reported short sleep durations saw a 51% increase in obesity between the ages of 12-14.9
It’s likely due to a variety of reasons, but here’s an important one — studies show that sleep deprived individuals feel more hunger and tend to eat more. This is likely due to sleep's effect on hormones that signal hunger and fullness. This could be why the adolescent study mentioned came to this conclusion, but let's talk about adults...
One study found that at least seven hours of sleep a night is essential for peak mental performance, immunity, and a decreased risk of cancer.10 If sleep deprivation continues, chronic sleep loss can affect your metabolism. This can increase your risk of stroke, heart disorders, and even diabetes.11
So is sleep essential to your body? I'd say so.
How Much Sleep Do Children Need?
In general, it's recommended that kids between the ages of 6 and 12 years old get an average of 10 and a half hours of sleep a night ... boy, do I miss those days!
As children get older, however, the number of hours of sleep decreases to about 9 hours a night. This would be for kids between the ages of 13 and 18 years old according to The American Academy of Sleep Medicine.12
Now, children often experience sleep disturbances or nightmares while they sleep. In fact, Pediatricians estimate that 20%–30% of children experience difficulties with sleep that are serious enough to disturb their family members. Another 10%–50% of children between 3 to 5 years old experience nightmares.13
In addition to nightmares, parents may discover their children sleep walking. It's actually estimated that 10%–30% of children have at least one episode of sleepwalking! Sounds pretty crazy, right? Well, of that 10%-30%, only 1%–5% meet the criteria for an actual sleepwalking disorder.
During puberty, the circadian rhythms shift, making teens more inclined to fall asleep closer to 11 p.m. and later.14
A study was conducted to compare the quality of sleep between teenage boys and girls. The study showed that of participants that were 12 years of age, only 34% slept 8 hours each night! This decreased to 23% by age 14 and 19% at age 16. Overall, boys slept less than girls as teenagers.15
So, we can see that as children get older, their sleep patterns change and become similar to that of adults. Because they are still developing though, getting enough sleep is still crucial to their health.
Sleep’s Effects on Health
How Does Exercise Affect Sleep?
Exercise has a very positive effect on sleep ... as I'm sure you can imagine. In fact, a recent study found that daily activity correlated positively with increased sleep quality.16 This is backed up by a survey which shows that people who exercise less than once a week were less likely to sleep more than six hours a night.
The survey also showed that they were more prone to sleep disorders such as insomnia and sleep apnea.17 They also tended to describe their sleep as fair or poor quality.
So, how much exercise should a person get to improve their sleep quality? Charlene Gamaldo, M.D., medical director of Johns Hopkins Center for Sleep at Howard County General Hospital, revealed that people who engage in at least 30 minutes of moderate aerobic exercise may see a difference in sleep quality that same night!
It also does not matter when you exercise, just that you do. 30 minutes of exercise, morning or night, provides the same benefit.18 Dr. Gamaldo argues that exercise is a mood stabilizer that can help your mind decompress. These are important for both falling asleep and sleeping restfully.
The relationship between sleep and exercise goes both ways. For example, Adults with insomnia tend to be less active than those without insomnia. The same is true for people with Obstructive Sleep Apnea (OSA) and other types of sleep-disordered breathing.19
On top of that, people with sleep deficiencies are at an increased risk for acute illnesses, physical injuries, and development of chronic diseases. All of this can make it extremely difficult to exercise.20 It truly is a vicious cycle.
For athletes, sleep is key to performance. For example, one study found that, “a reduction in sleep quality and quantity could result in an autonomic nervous system imbalance, simulating symptoms of the overtraining syndrome.”21
Despite its importance to performance, the stress of competition can sometimes play a role in sleep quality too. This survey is super revealing: 64.0% of athletes indicated they slept worse than usual on at least one occasion in the nights prior to an important competition over the past 12 months.
The main sleep concern identified by athletes was problems falling asleep (82.1%).
The main reasons for this were:
• ‘Thoughts about the competition’ (83.5%)
• ‘Nervousness’ (43.8%)22
Sleep’s Effect on Chronic Pain
Sleep is intrinsically tied to nearly every function of our body. This is no different for those who suffer from chronic pain. In fact, 1 in 4 people with chronic pain also suffer from a sleep disorder.23 The compounded effects of chronic pain and sleep deprivation can be devastating to those just trying to live their normal lives.
Chronic pain is a widespread problem. It’s estimated over 50 million Americans suffer from chronic pain.24 Constant pain can make it difficult to get the rest our bodies so desperately need.
Considering sleep and pain are so intertwined, it should be no surprise that sleep disorders, and lack of sleep in general, can also trigger chronic pain. One study suggests that if you fall asleep in pain, how long you sleep may determine how much better or worse the pain is the next day.
Simply put, if you sleep for fewer hours, you’re likely to be in more pain the next morning.25 Not only can your pain get worse after a poor night’s sleep, but consistent, poor sleep can even cause more chronic pain syndromes to manifest over time.26
How Does Sleep Affect Memory?
Researchers have found that sleep helps memories become consolidated in our brains so that they ‘stick.’27 This process of memory stabilization can take what you remember from your day and turn it into a lasting memory.
On top of that, sleep can help you link memories together as well. Yes, that means that sleep may also contribute to problem solving.28
Studies have also proven that a lack of sleep is detrimental to your mental health, including your memory. Brain and behavioral functions suffer when someone does not get the required amount of sleep ... typically seven to ten hours a night.29
So what suffers? Well, your acquisition, ability to learn new information, and recalling old information all suffer.
When your brain struggles to be able to learn new information, that means the process of consolidation will also suffer.30 This explains why people can expect to perform better, test better, and work better when they get enough sleep. I think this is something all of us were told growing up!
Sleep’s Effect on PTSD
It should be no surprise that sleep directly affects every part of our bodies. Well, this is especially true when it comes to mental health. PTSD can be a devastating condition to live with. One Oxford study estimated that in Europe, between 1-3% of the population suffers from PTSD,31 while about 5% of the U.S. population suffers from PTSD at a given time.32
The people who suffer from PTSD every day also tend to suffer from sleep disruptions. Research suggests that number is about 50-70% of those with PTSD. This can be anything from falling asleep to waking up earlier than wanted, trouble staying asleep, and poor sleep quality.33
Similar to other disorders and illnesses, sleep has a huge effect on how PTSD develops. The development of sleep disorders after traumatic events is even a predictor of the development of PTSD later.34 Additionally, those who suffer from a sleep disorder, like insomnia, are more likely to develop PTSD after facing a traumatic event.35 Sleep is important to the function of our brains and can greatly affect how we process the problems we face.
What is a Sleep Disorder?
A sleep disorder is essentially anything that hinders your ability to sleep regularly. There are currently 88 recognized sleep disorders.36 Some of the most common are insomnia, narcolepsy, sleep apnea, and restless leg syndrome. Sleep disorders are very common with over 70 million Americans affected every year.37
Insomnia symptoms are likely to manifest in many people. Typically, anywhere from 33% to 50% of people will suffer from symptoms of insomnia. Chronic Insomnia Disorder, however, will only manifest in 10% to 15% of the adult population ... becoming even more common over the age of 60.38 Narcolepsy, on the other hand, affects both males and females equally.
Symptoms often start in childhood, adolescence, or young adulthood (ages 7 to 25), but can occur at any time in life. It is estimated that anywhere from 135,000 to 200,000 people in the United States have narcolepsy.39
Sleep disorders affect millions of people around the world and have a serious impact on their everyday lives. They can affect our mental and physical health, decision making, and overall happiness.
What is Sleep Deprivation?
Sleep deprivation is the lack of adequate sleep over a period of time. People can struggle with sleep deprivation for a few nights, or it can be a chronic condition that lasts for weeks or even months. Normally, this is caused by lifestyle choices, health conditions, or environmental factors.
Unfortunately, it's a growing public health epidemic. Believe it or not ... two-thirds of adults don't get the recommended eight hours of sleep each night.40 Additionally, the use of sleep medications is increasing. As of 2018, 8.2% of adults over the age of 18 took medication to help fall or stay asleep.41
The effects of sleep deprivation can result in physical, mental, and emotional symptoms. These are symptoms such as fatigue, irritability, reduced productivity, stress, and anxiety.42
Moderate sleep deprivation can have effects similar to being drunk, such as slower reaction times and decreased accuracy on cognitive tasks.43 In 2003, a study was conducted to see if it was possible to decrease the amount of sleep someone could get each night without any negative effects of sleep deprivation ... I'm sure you can guess how that went.
Results of the study showed that those who slept for six hours or less for two weeks had the same level of cognitive decline as those who did not sleep at all for two nights in a row!44 Studies have also found that sleep deprivation can affect generosity. Donations actually decrease by 10% in the days after daylight savings begins compared to the weeks before and after the transition.45 So I guess you could say that being cranky from a lack of sleep doesn't put you in a very charitable mood!
Which Professions Suffer From Lack of Sleep?
Most sleep-deprived professions are those that often require long hours, night shifts, and on-call duties. Healthcare workers, emergency responders, and transportation workers are at a greater risk of sleep deprivation due to the demanding nature of their jobs.
When these workers are unable to get enough sleep, their performance is drastically affected. This can also lead to impaired decision-making, increased fatigue, and decreased alertness. All of these things can be potentially dangerous for these workers and have severe consequences if not addressed properly.
Studies have shown that the professions associated with the highest number of sleep deprived people include:
• Truck Drivers: 1 in 20 have a significant inability to stay awake.46
• Healthcare Workers: 4 in 10 reported insomnia symptoms.47
• Military Cadets: Many average over 3 hours of significant sleep deprivation each day.48
• Police Officers: Only get on average 4 and a half hours of sleep49
• Firefighters: 45.8% of firefighters report not getting enough sleep.50
How to Improve Your Sleep
How to Fall Asleep Fast
Many factors influence the time it takes for you to fall asleep - but here’s some surprising information on how to speed up the process. Start with the basics by making where you sleep the ideal environment for you. That might mean black out curtains ... a white noise machine if you live on a busy street ... or even headphones or earplugs if the environment is too noisy.51
You can also add some things to your routine to make falling asleep easier. Exercising or yoga could help you prepare to fall asleep fast. Heck, there are even natural supplements that you can take to facilitate better sleep.
Surprisingly enough, NOT stressing about falling asleep fast can help you drift off more quickly too. The same can be said about unplugging from smartphones and laptops before you go to bed.52 Cutting out screen time 30 minutes before bed can contribute to how long it takes to fall asleep. On top of that, it can also increase your quality of sleep!53
What Foods Help You Sleep?
There is a lot that goes into making sure you get a good night's sleep. Surprisingly, one of the easiest ways to improve your quality of sleep is by being intentional about your diet.
What you eat can actually have a big impact on how rested you feel when you wake up in the morning. One study found that eating more fiber, less saturated fats, and less sugar can play a role in how well you sleep.54
With that in mind, let’s take a look at some of the best foods you can eat before bed according to researchers.
• POPCORN: It’s low-calorie (if you make it right) and high in fiber. It can also boost serotonin to help you feel calm and sleepy.55
• TOAST: Carbs affect insulin levels, which can play a role in regulating your body’s sleep-wake clock. Keep the toppings light and aim for high-fiber whole wheat toast.56
• CHEESE: Cheese contains tryptophan, which reduces stress and promotes sleep. 72% of cheese eaters reported sleeping well and having pleasant dreams.57
• ALMONDS: Almonds are not only high in fiber, but also contain melatonin, a hormone that helps induce sleep.
• APPLES: Apples are high in fiber and low on the GI index, which means they don’t cause much of a rise in your blood sugar. One study has even shown that in some cases, switching to low glycemic foods can decrease insomnia.58
• KIWI FRUIT: Like apples, Kiwi are high in fiber. Their effects on sleep have been studied, with some researchers finding that people who ate two kiwifruits one hour before going to bed every night fell asleep 42% faster than those who didn’t ... they also stayed asleep for 13% longer.59
What Side Should You Sleep On?
Have you heard the term “side sleeper” or “back sleeper”? Are you curious if there is a certain side you should sleep on to improve your sleep?
After collecting several national studies, it's been determined that about 74% of people choose to sleep on their side, 16% on their stomach, and 10% on their back.60 Some people may choose to sleep on their side, stomach, or back because they are comfortable in that position ... or just because this is the spot they tend to end up in night after night.
Side sleeping, however, leads to less snoring with and without obstructive sleep apnea. Side sleeping also can help reduce back and neck pain.61 So if you haven't tried sleeping on your side, this may be your calling.
How to Wake Up Early
If you're looking to start waking up earlier ... where should you start? Here's what I recommend...
• Expose yourself to light when you wake up. According to Dr. Afifa Shamim-Uzzaman, Sunlight helps regulate your internal clock.62
• Get your body moving
• Keep a consistent sleep schedule
• Take a short nap during the day
• Don’t nap close to bedtime
• Keep your caffeine intake limited to morning.
• Take a small dose of Melatonin 2-3 hours before bedtime.
• Give yourself an incentive
• Wake up five minutes before you have to be up.63
• Give yourself 30-60 days to get in the habit of waking up early. Your body needs time to adjust to the new schedule.64
What are the benefits of waking up early?
It turns out that people who follow this schedule skew on the healthy side of many health problems. Researchers have found that night owls, which make up about 30% of the population, are actually at higher risk for a multitude of health issues. These include obesity, diabetes, heart disease, and addictive behaviors.65
These studies are backed up by what researchers have found about people who work night shifts. Sabra Abbott, sleep medicine specialist at Northwestern Memorial Hospital, reports that night shifts bring an increased risk for diabetes, cardiovascular disease, obesity, and hypertension. They are also at a higher risk for cancer, with experts considering it a probable carcinogen.66 One-third of shift workers also deal with sleep-wake disturbance (SWD) and their symptoms meet SWD criteria.67
On top of that, Early risers, about 40% of the population, also tend to get more exercise. Typically, this is moving 20-30 minutes more a day than night owls. Exercise helps prevent health problems and leads to better sleep.68
How Long Should a Nap Be?
As much as a long nap sounds amazing, you should actually aim to nap for only about 10-20 minutes. Many studies have found that naps as short as 10 minutes improve performance!
In fact, naps of less than 30 min provide several benefits, including increased learning and an improved feeling of wakefulness. One study even suggests that a short nap during the day might be a protective factor against depressive symptoms too.69
On the other hand, longer naps are associated with a loss of productivity and sleep inertia.70 In fact, sleeping too much can actually lead to depression, irritability, and cardiovascular issues.71
Nap length isn’t the only important factor in its effectiveness either; Nap timing matters too. A 2021 study found that the best time to nap is in the middle of the day or early in the afternoon.72
How to Sleep with a Partner
Sleeping with a partner can be tough. In fact, according to the National Sleep Foundation, one in four married couples sleep in separate beds,73 and 46% of Americans in one poll said they wished they could sleep apart from their partner.74 However, taking steps to ensure a better night’s sleep can change the way you view sleeping next to your partner.
Here are 8 tips for sleeping with a partner:
• Establish a set sleep schedule and go to bed at the same time as your partner. One study revealed that men often struggle to get to bed on time, delaying their bedtime because it functions as a risk-taking behavior.75 If you or your partner fall into this category, make it a point to get to bed on time.
• Exercise with your partner! As mentioned earlier, exercising can play a big role in sleep quality.
• Get a bigger bed. This helps mute your partner’s movements so you can stay asleep.
• Dim the lights before bed. Deep sleep starts about 40 minutes after the lights turn out. Starting that process earlier will help you and your partner move into deep sleep faster.76
• Try white noise. If the noises your partner makes keep you awake, this could be a great option.
• Upgrade your mattress or platform: Find a mattress that works for both of you, whether that means getting one that minimizes movement or regulates temperature. An adjustable platform can be a great option if your partner snores.
• Stop watching TV in bed … and looking at your phone. Unplugging before bed helps your mind calm down, and the light may keep you from falling asleep quickly.
• Use individual blankets. Try using your own blanket instead of sharing. This is the perfect option if your partner steals the covers or needs a weighted blanket.
Why Do People Snore? How Many People Snore?
Another reason sleeping with a partner can be difficult is just how many people snore. Johns Hopkins estimates that 45% of people snore every now and then, and 25% snore on a regular basis.77
This is an especially big problem for women who sleep with a partner, because men are more likely to snore: About 57% of men snore. In comparison, only 40% of women snore.78
The total time spent snoring during sleep also shows men snore more. On average, women snore a bit over twice each night for a total of 17 minutes and 47 seconds. Men snore an average of 2.75 times for 24 minutes and 7 seconds.79
Do kids snore? Yes, but not as much. While almost 50% of adults snore, only 10-12% of children snore.80
What Else Would You Like to Know
Obviously, we covered a lot today. I'm sure you were able to absorb a ton of cool facts and info about sleep which will improve yours!
As much as we talked about ... there is still a lot more to the topic of sleep as a whole.
If you have any questions, need any help, or have any other health or fitness goals you're looking to accomplish ... reach out to us! We have a full team of NASM Certified Personal Trainers and Certified Nutrition Coaches who are happy to help. Just give us a call at 1-800-409-9732 or send us an email at CustomerService@1stphorm.com anytime!
50 Auer, Joe. “The Most Sleep Deprived Professions in the United States (2023).” Mattress Clarity, 7 Sept. 2022, https://www.mattressclarity.com/blog/the-most-sleep-deprived-professions-in-the-united-states/.
3, 20 Axelsson J; Sundelin T; Ingre M; Van Someren EJ; Olsson A; Lekander M; “Beauty Sleep: Experimental Study on the Perceived Health and Attractiveness of Sleep Deprived People.” BMJ (Clinical Research Ed.), U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/21156746/.
76 Besedovsky, Luciana, et al. “Hypnotic Enhancement of Slow-Wave Sleep Increases Sleep-Associated Hormone Secretion and Reduces Sympathetic Predominance in Healthy Humans.” Nature News, Nature Publishing Group, 26 July 2022, https://www.nature.com/articles/s42003-022-03643-y.
29 Bishir, Muhammed, et al. “Sleep Deprivation and Neurological Disorders.” BioMed Research International, Hindawi, 23 Nov. 2020, https://www.hindawi.com/journals/bmri/2020/5764017/.
54 Celmer, Lynn. “Study Suggests That What You Eat Can Influence How You SleepLynn.” American Academy of Sleep Medicine – Association for Sleep Clinicians and Researchers, 14 Jan. 2016, https://aasm.org/study-suggests-that-what-you-eat-can-influence-how-you-sleep/.
71, 72 Cherney, Kristeen. “Best Time to Sleep for Different Age Groups: Benefits and Side Effects.” Healthline, Healthline Media, 14 Nov. 2019, https://www.healthline.com/health/best-time-to-sleep#too-much-sleep-side-effects.
37 Cleveland Clinic. “Insomnia: What It Is, Causes, Symptoms & Treatment.” Cleveland Clinic, https://my.clevelandclinic.org/health/diseases/12119-insomnia#:~:text=How%20common%20is%20insomnia%3F,at%2010%25%20to%2015%25.
38 Cleveland Clinic. “Insomnia: What It Is, Causes, Symptoms & Treatment.” Cleveland Clinic, https://my.clevelandclinic.org/health/diseases/12119-insomnia#:~:text=How%20common%20is%20insomnia%3F,at%2010%25%20to%2015%25.
49 Davis, Jessica. “These Are the Most Sleep-Deprived Professions.” Harper's BAZAAR, Harper's BAZAAR, 21 Mar. 2018, https://www.harpersbazaar.com/uk/beauty/mind-body/a19514296/these-are-the-most-sleep-deprived-professions/.
66, 67 Delgado, Carla. “Irregular Sleep Schedules Can Lead to Health Risks.” Discover Magazine, Discover Magazine, 7 Sept. 2022, https://www.discovermagazine.com/health/irregular-sleep-schedules-can-lead-to-health-risks.
70 Dhand, Rajiv, and Harjyot Sohal. “Good Sleep, Bad Sleep! the Role of Daytime Naps in Healthy Adults.” Current Opinion in Pulmonary Medicine, U.S. National Library of Medicine, 12 Nov. 2006, https://pubmed.ncbi.nlm.nih.gov/17053484/.
47 Diaz, Franchesca. “Sick and Tired: Study Reveals Toll of Poor Sleep among Health Care Workers.” Columbia University Irving Medical Center, 24 Nov. 2021, https://www.cuimc.columbia.edu/news/sick-and-tired-study-reveals-toll-poor-sleep-among-health-care-workers.
36 Doghramji, Paul P, et al. “Stay Awake! Understanding, Diagnosing, and Successfully Managing Narcolepsy.” The Journal of Family Practice, U.S. National Library of Medicine, Nov. 2007, https://pubmed.ncbi.nlm.nih.gov/18684353/.
18 “Exercising for Better Sleep.” Exercising for Better Sleep | Johns Hopkins Medicine, 8 Aug. 2021, https://www.hopkinsmedicine.org/health/wellness-and-prevention/exercising-for-better-sleep.
13 Fallon, Jr, L. Fleming, and Karl Finley. “Sleep Disorders.” The Gale Encyclopedia of Nursing and Allied Health, 2018, https://go.gale.com/ps/i.do?p=HWRC&u=byuprovo&id=GALE|CX3662601052&v=2.1&it=r&sid=bookmark-HWRC&asid=552b89c3. Accessed 15 Mar. 2023.
21 Fullagher, Hugh HK, et al. “Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise.” Sports Medicine (Auckland, N.Z.), U.S. National Library of Medicine, Feb. 2015, https://pubmed.ncbi.nlm.nih.gov/25315456/.
62 George, Kavitha, and Clare Marie Schneider. “How to Wake up Early, Even If You're Not a Morning Person.” NPR, NPR, 5 Nov. 2021, https://www.npr.org/2021/11/02/1051553451/how-to-wake-up-early.
63 George, Kavitha, and Clare Marie Schneider. “How to Wake up Early, Even If You're Not a Morning Person.” NPR, NPR, 5 Nov. 2021, https://www.npr.org/2021/11/02/1051553451/how-to-wake-up-early.
9 Goldman, Sharon. “Weight Loss and Sleep.” Comprehensive Sleep Care, Sharon Goldman Https://Comprehensivesleepcare.com/Wp-Content/Uploads/2017/05/CSC.png, 26 Jan. 2023, https://comprehensivesleepcare.com/2022/01/04/weight-loss-and-sleep/#:~:text=Poor%20Sleep%20Is%20a%20Major,(BMI)%20and%20weight%20gain.
31 Haack, Monika, et al. “Sleep Deficiency and Chronic Pain: Potential Underlying Mechanisms and Clinical Implications.” Academic.oup.com, National Library of Medicine, 17 June 2019, https://academic.oup.com/book/24487/chapter-abstract/187582261?redirectedFrom=fulltext.
26 Haack, Monika, et al. “Sleep Deficiency and Chronic Pain: Potential Underlying Mechanisms and Clinical Implications.” Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology, U.S. National Library of Medicine, Jan. 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6879497/.
58 Hallal, Fatima. “Should You Eat an Apple before Bed?” Healthline, Healthline Media, 13 Oct. 2021, https://www.healthline.com/nutrition/apple-before-bed.
22, 42 Halson, Shona L. “Sleep Monitoring in Athletes: Motivation, Methods, Miscalculations and Why It Matters - Sports Medicine.” SpringerLink, Springer International Publishing, 15 May 2019, https://link.springer.com/article/10.1007/s40279-019-01119-4.
46 Huhta, Riikka, and Kari Hirvonen. “Prevalence of Sleep Apnea and Daytime Sleepiness in Professional Truck Drivers.” Sleep Medicine, U.S. National Library of Medicine, May 2021, https://pubmed.ncbi.nlm.nih.gov/33676284/.
8 Hunter, Erin. “Study: Fewer than Eight Hours of Sleep Associated with Higher Childhood Obesity Rates.” Pharmacy Times, Pharmacy Times, 30 Aug. 2022, https://www.pharmacytimes.com/view/study-fewer-than-eight-hours-of-sleep-associated-with-higher-childhood-obesity-rates.
12 Hunter, Erin. “Study: Fewer than Eight Hours of Sleep Associated with Higher Childhood Obesity Rates.” Pharmacy Times, Pharmacy Times, 30 Aug. 2022, https://www.pharmacytimes.com/view/study-fewer-than-eight-hours-of-sleep-associated-with-higher-childhood-obesity-rates.
15 Hunter, Erin. “Study: Fewer than Eight Hours of Sleep Associated with Higher Childhood Obesity Rates.” Pharmacy Times, Pharmacy Times, 30 Aug. 2022, https://www.pharmacytimes.com/view/study-fewer-than-eight-hours-of-sleep-associated-with-higher-childhood-obesity-rates.
40 Ivanhoe Broadcast News. “Best Life: Sleep Divorce Saves Marriages and Improves Health.” Https://Www.actionnews5.Com, 9 Sept. 2022, https://www.actionnews5.com/2022/09/09/best-life-sleep-divorce-saves-marriages-improves-health/.
1 Jansen, Erica. “Sleep 101: Why Sleep Is so Important to Your Health.” The Pursuit | University of Michigan School of Public Health | Adolescent Health | Child Health | Chronic Disease | Epidemic | Mental Health | Obesity, University of Michigan School of Public Health, 2 Mar. 2020, https://sph.umich.edu/pursuit/2020posts/why-sleep-is-so-important-to-your-health.html.
33 Lancel, Marike, et al. “Disturbed Sleep in PTSD: Thinking beyond Nightmares.” Frontiers, Frontiers, 2 Nov. 2021, https://www.frontiersin.org/articles/10.3389/fpsyt.2021.767760/full.
45 Laura Boubert Principal Lecturer in Psychology. “Tiredness Can Change How Generous You Are – New Research.” The Conversation, 7 Dec. 2022, https://theconversation.com/tiredness-can-change-how-generous-you-are-new-research-189072.
59, 69 Lin, Hsiao-Han, et al. “[PDF] Effect of Kiwifruit Consumption on Sleep Quality in Adults with Sleep Problems.: Semantic Scholar.” Asia Pacific Journal of Clinical Nutrition, 1 Jan. 1970, https://www.semanticscholar.org/paper/Effect-of-kiwifruit-consumption-on-sleep-quality-in-Lin-Tsai/5b681a8e5b2949416ac960cfb5b44823183a2881.
60 Linens, Anna's. “National Sleep Survey Pulls Back the Covers on How We Doze and Dream.” PR Newswire: Press Release Distribution, Targeting, Monitoring and Marketing, 30 June 2018, https://www.prnewswire.com/news-releases/national-sleep-survey-pulls-back-the-covers-on-how-we-doze-and-dream-184798691.html#:~:text=As%20far%20as%20how%20we,10%20percent%20on%20their%20back.
2 Mallika Marshall, MD. “Study: If You Get Optimal Sleep, You Have a Much Lower Risk for Cardiovascular Issues.” CBS News, CBS Interactive, 1 Sept. 2022, https://www.cbsnews.com/boston/news/study-if-you-get-optimal-sleep-you-have-a-much-lower-risk-for-cardiovascular-issues/.
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