Research and rigor is at the heart of everything we do at Proper. We obsessively pore over the latest in behavioral sleep science, integrative health, clinical psychology, and nutritional biochemistry— anything that could directly or indirectly impact sleep. All of this, in combination with what we learn from our customers, informs each decision that we make, from the sourcing of ingredients in the right combination and dosage, to developing a sleep coaching program and digital tools that can help customers build healthy habits for long-term sleep health.

In serving tens of thousands of Proper sleepers over the last 2 years, we’ve learned that many of you are obsessive (and skeptical) researchers like us, often asking about the research behind our products as well as the science and data behind other sleep products and natural solutions.

In the spirit of transparency, we’ve decided to publish our compilation of all things sleep science, with key facts and figures sourced from:

  • The latest clinical trials and meta-analyses from vetted public health sources (nih/ncbi.gov, American Academy of Sleep Medicine, CDC, etc)
  • Publicly-available statistics/market reports
  • Internal Proper data and sleep research

We cover sleep hygiene, sleep aids (natural supplements/over-the-counter and prescription), the health implications of insufficient and poor quality sleep, factors that impact sleep (menopause, parenthood, mental health, etc), and more.

This page will be continually updated with the latest sleep science, so be sure to bookmark it and check back regularly for more!

The stats behind sleep + overall health, wellness, and quality of life

  • Lack of sleep has been linked to a 9% increase in total abdominal fat and 11% in abdominal visceral fat, which is linked to cardiac and metabolic diseases.
  • According to a 5-year study, routinely sleeping fewer than 5 hours/night is associated with double the risk of incident dementia, while routinely taking 30 minutes or longer to fall asleep is associated with a 45% increased risk of incident dementia.
  • In a 2018 study conducted by the National Institutes of Health, researchers scanned participants’ brains after a night of sleep. The study group was sleep deprived (defined as going 31 hours without sleep) while the control group got a complete night’s rest. Results showed that levels of beta-amyloid (a protein linked to impaired brain function) increased about 5% for the sleep-deprived group in the thalamus and hippocampus, both of which are susceptible to damage in early Alzheimer’s.
  • Men who slept fewer than 5 hours a night for 1 week were found to have 10-15% lower levels of testosterone than when they had a full night’s sleep.
  • 63% of male patients with Obstructive Sleep Apnea (OSA) have been found to also suffer from Erectile Dysfunction, compared to 47% of those without OSA.
  • Both prolonged and short sleep duration have been found to negatively impact the probability of conception: <6 hours = 0.62%, 6 hours = 1.06%, 7 hours = 0.97%, and >9 hours = 0.73%.

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The stats behind poor sleep + sleep disorders

  • 68% of U.S. adults struggle with sleep at least once a week.
  • 56% of U.S. adults have experienced an increase in sleep disturbances since the start of the COVID-19 pandemic.
  • Willis-Ekborn disease, known more commonly as Restless Leg Syndrome (RLS), affects up to 1 in 10 people at some point in their life, with women twice as likely as men to develop symptoms, according to recent sleep disorder statistics.

"RLS is easy to misdiagnose, so it’s important to consult an expert. Because the causes of RLS vary considerably, there isn’t one single diagnostic test. Primary care doctors can usually diagnose the condition based on your medical/family history, a physical examination, and bloodwork. If not, ask for a neurologist referral."

Michael T. Smith. PhD, CBSM, DBSM, Member of Proper’s Scientific + Medical Advisory Board

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The stats behind daytime effects of poor sleep

  • Driving while drowsy/fatigued is responsible for more than 6,000 fatal car crashes every year in the U.S.
  • In a study conducted by Stanford University, healthy college students on the men’s basketball team demonstrated improved athletic performance after a sleep extension period, including a faster timed sprint (16.2 seconds at baseline vs 15.5 during sleep extension) and improved shooting accuracy (9% increase in free throw percentage).
  • The effects of sleep deprivation in terms of cognitive impairment are equivalent to legally prescribed levels of alcohol intoxication, with 17-19 hours awake equivalent to a blood alcohol level of 0.05% and 20 hours awake equivalent to a blood alcohol level of 0.1%.
  • When you add up the costs of reduced productivity, motivation, and healthcare due to fatigue, it comes out to $1,967 per year, per employee. That’s a total of $136 billion a year that U.S. companies have to spend to compensate for the side effects of insufficient sleep.
  • A study conducted by the American Heart Association found that people who slept an hour and 20 minutes less consumed 549 more calories than the control group. What didn’t change between the groups was the amount of energy expended, which suggests that those who slept less (and consumed more) weren’t burning additional calories.

“Without enough sleep, your body’s in such a high state of stress and cortisol is so high that even if your workout is good, you’re stressing your system so much that the resulting hunger and cravings will cause you to over-eat whatever calorie allotment you burned. It won’t go to your muscles.”

Ashley Lucas, PhD, RD

  • In a study comparing 4 nights of normal (i.e. 8.5 hours) sleep against restricted (i.e. 4.5 hours) sleep, results showed that the sleep-deprived group consumed nearly twice as much fat and protein as the control group.

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The stats behind sleep quality vs quantity

  • Not everyone needs 8 hours of sleep. Quality trumps quantity and some, due to genetics, may be “elite sleepers” who can thrive on only 4-6 hours per night.
  • The recommended amount of sleep/sleep need per night changes by age group

  • Come adulthood, the amount of time spent in stage 3 (deep sleep, otherwise known as slow wave sleep) decreases while the proportion of sleep in stage 1 and 2 increases. The effect of age on REM sleep, however, is minimal, with researchers finding a 0.6% decrease per decade from age 19 to 75, followed by smaller increases from age 75 to 85.

“One of the biggest sleep myths out there is that everyone, regardless of age, needs eight hours of sleep per night. While this may be true for some, it’s far too simplistic to apply a one-size-fits-all treatment to something as complex and individual as sleep.”

Allison Siebern, PhD, CBSM, Member of Proper’s Scientific + Medical Advisory Board

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The stats behind sleep health disparity

  • Studies have found that poor sleep quality is more prevalent among Black, Hispanic/Latino, and Chinese participants.
  • African American children are 4-6 times more likely to have Obstructive Sleep Apnea compared to caucasian children.
  • Among young adults less than 26 years old, African Americans are 88% more likely to have Obstructive Sleep Apnea compared to caucasians.
  • The prevalence of diabetes in Hispanic patients with Obstructive Sleep Apnea was 42.7%, compared with 24.28% of caucasians.

The stats behind menopause + sleep

"Generally speaking, both men and women experience decreases in deep sleep—aka delta sleep—after adolescence. However, this is compounded for women who, in addition to aging, are traversing a menopausal transition marked by fluctuations in several key hormones: estrogen, progesterone, serotonin, and melatonin.”

Allison Siebern, PhD, CBSM, Member of Proper’s Scientific + Medical Advisory Board

READ MORE: Sleep Problems During Menopause: Causes + Treatment

The stats behind parenthood + sleep

  • 1 out of every 5 pregnant women will experience Restless Leg Syndrome at some point during their last trimester.
  • 71% of women with children under the age of 18 at home consider themselves to be poor sleepers (Proper Sleep Study, 2019)
  • 80% of women with children under the age of 18 at home wake up in the middle of the night at least three times a week (Proper Sleep Study, 2019)
  • According to a 2019 study of 5,805 Americans, over half of mothers get less than 7 hours of sleep at night (with quantity decreasing with each child in the house). Fathers, however, do get enough sleep.

The stats behind mental health + sleep

  • ~75% of adults with depression suffer from insomnia.
  • Over 90% of those with military combat-related PTSD have been found to experience symptoms of insomnia.
  • According to a National Sleep Foundation survey, 43% of Americans between the ages of 13 and 64 have reported lying awake at night and losing hours of sleep due to stress.
  • According to a study of 2,291 participants during COVID-19, 57.1% reported poor sleep quality, 41.8% reported high anxiety, and 7.6% reported PTSD symptoms linked to the pandemic. The numbers pre-pandemic were 30% for sleep issues, 10% for anxiety disorders, and 23.9% for psychological distress.

READ MORE: How Stress Affects Sleep

The stats behind genetics + sleep

  • Researchers estimate that 35% of those with chronic insomnia have a family history of it, with the mother being the most commonly affected family member. However, because sleep is affected by so many factors, it’s difficult to definitively pinpoint a genetic attribution.
  • Researchers estimate that the hereditary component for Obstructive Sleep Apnea Syndrome (OSAS) hovers around 40%, with the remaining 60% attributable to environmental factors.
  • 43% of children with OSAS have at least one relative with comparable symptoms.
  • The rate of sleepwalking for a child without parents who do is 22% compared to 45% when hereditary.

“I’ll often hear clients say…’I was born this way’ or ‘I have the same issues as my mother/father.’ Sometimes that can be a helpful frame of reference, but it can often make a client feel doomed to a fate of poor sleep and create resistance or reluctance to investigate what personal habits or behaviors may be contributing to magnifying any genetic predisposition.”

Kelly O’Brien, NBC-HWC, Proper Sleep Coach

READ MORE: Are Sleep Problems Hereditary?

The stats behind sleep aids (Rx, OTC, natural supplements) 

  • Over 50% of U.S. adults have used supplements, medications, or other substances to help them fall asleep.
  • In 2020, melatonin sales grew 42.5% to $687 million. (Nutrition Business Journal, 2020)
  • On average, people with insomnia fall asleep about 7 minutes faster when they take melatonin (compared to placebo).
  • 5-10% of people feel sleepy after taking melatonin.

“I have noted over the last 10+ years in my sleep medicine clinic that not everyone responds the same to melatonin (in fact, I have noted anecdotally that ~50% of patients actually note a positive response).”

Ruchir Patel, MD, MB, BCh, FACP, Member of Proper’s Scientific + Medical Advisory Board

READ MORE: How Safe + Effective Are Most Over-The-Counter Sleep Aids?

The stats behind behaviors + sleep

  • The light receptors in the eyes are linked to the time-keeper in the brain that regulates when we sleep and when we are awake. Bright light (and blue light from smartphones) confuses this signal and may keep us awake when we’re exposed to it within 1-2 hours of bedtime. Additionally, exposure to even moderate ambient lighting during sleep harms cardiovascular function by increasing heart rate, leading to insulin resistance the following morning.
  • According to new research presented in March 2022 at the American Heart Association Conference, resistance training may benefit sleep even more than aerobic exercise does.In the year-long study, researchers randomly assigned 386 inactive, overweight adults with high blood pressure to one of 4 groups:
  1. Supervised aerobic exercise 3x/week for 60 mins (treadmills, bicycles, or elliptical machines)
  2. Supervised resistance exercise 3x/week for 60 mins
  3. Combined resistance/aerobic exercise 3x/week for 60 mins
  4. Control group (no supervised exercise)
    For the 42% of participants who began the study getting less than 7 hrs of sleep/night, those in group 2 (resistance exercise) were able to extend their average sleep time by 17 minutes/night (in addition to falling asleep faster).
  • Sleep hygiene and behavioral education for workers with insomnia was shown to decrease average Pittsburgh Sleep Quality Index (PSQI) scores by 1.0 for the intervention group (compared to a 0.9 increase in the control group), an indication of significant sleep quality improvements.

"We know supplements alone are not the answer. The best approach incorporates the natural products that address the biochemical components of disrupted sleep AND the behavioral change required to get a good night’s rest.”

Adam Perlman, MD, MPH, Member of Proper’s Scientific + Medical Advisory Board

“The human body is incredibly complex and sleep is just as complex. Dietary supplements can support sleep, but they won’t fix everyone’s sleep problems. The mental and emotional aspects of a person’s day have as much of a role in their sleep health as the physical aspects.”

Alice Hirschel, PhD, Member of Proper’s Scientific + Medical Advisory Board

READ MORE: 4 Ways A Sleep Coach Can Help You

The stats behind food + sleep

  • In a 4-week study, 24 subjects consumed 2 kiwis an hour before bed, with results showing that waking time after sleep onset decreased 28.9% and sleep onset latency decreased 35.4%. Additionally, total sleep time and sleep efficiency increased by 13.4% and 5.41% respectively.
  • One study examining the effects of 400 mg of caffeine 30 minutes before bedtime found that it reduced sleep efficiency 5%, prolonged sleep latency (the amount of time it takes to fall asleep) by 12-16 minutes, and reduced total sleep time by 25-30 minutes compared to the placebo group.
  • Caffeinated drinks don’t have to be consumed so close to bedtime for them to affect sleep. Even at 6 hours, caffeine consumption has been shown to possibly reduce sleep time by more than 1 hour.
  • In a 49-day study, the consumption of caffeine equivalent to that in a double espresso consumed 3 hours before bedtime led to a phase delay of the melatonin/circadian rhythm by approximately 40 minutes.

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The stats behind sleep environment—music, white noise machines, etc.

  • In a survey of over 500 patients suffering from sleep disorders, over 50% reported using music as a sleep aid—making it the most prevalent of all the integrative medicine approaches evaluated.
  • Broadband sound administration has been found to reduce sleep onset latency by 38% compared to normal environmental noise.

READ MORE: 12 Best Podcasts To Help You Fall Asleep

The stats behind exercise + sleep

READ MORE: What’s The Best Time To Exercise For High-Quality, Healthy Sleep?

The stats behind sleep wearables + trackers

  • In 2019, the market for wearable devices, including sleep trackers, was estimated to reach over $62 billion by 2021.
  • According to a 2019 systematic review published in the Journal of Medical Internet Research, Fitbit models showed promising performance in differentiating wake time from total sleep time, as well as time spent in sleep stages; however, they are of “limited specificity and are not a substitute for [polysomnography] PSG,” which is conducted as part of a sleep study in a dedicated sleep lab (where you can also track brain activity with an EEG (electroencephalogram).
  • In June 2019, Garmin released results from a study showing that the overall accuracy against real-world data was 69.7%, with a 95.8% sensitivity in detecting sleep and 73.4% specificity in detecting awake.
  • In January 2020, Oura published results of an internal study of 49 healthy subjects which showed that, compared to a medical-grade electrocardiogram device (ECG), the Oura ring performed near-perfect for resting heart rate and (RHR) and heart rate variability (HRV). Additionally, their new sleep staging algorithm—which was released in June 2021—was found to achieve 79% agreement with gold-standard PSG for identifying sleep stages (wake, light, deep, and REM).

“Sleep data gives us the opportunity to find patterns we may not be conscious of yet. There are so many factors that impact our sleep schedule, patterns, and quality—and while some may be obvious, some are more insidious. The more detailed we are with our sleep monitoring, the more we can understand and peel back the layers that are impacting our sleep so we can get the sleep we need.”

Lauren Hoogs, NBC-HWC, Proper Sleep Coach

READ MORE: How Do Sleep Trackers Work + Are They Accurate?

The stats behind “normal” sleep

  • 90% is considered a normal oxygen level during sleep, with anything below 88% abnormal and below 80% severely abnormal.
  • Most people’s sleeping heart rate falls to the lower end of what’s considered a “normal resting heart rate”—that is, 60-11 beats per minute (bpm). However, for those with a generally low heart rate while awake, stages of deep sleep may cause their heart rate to fall below 60 bpm.
  • Healthy adults spend just above 20% of their sleep in deep stages, with anything below 10% considered abnormal.
  • In total, we spend about 20-25% of our time in the REM stage, which equates to roughly 90 minutes over the course of 7-8 hours of sleep.
  • Light sleep constitutes the majority of your sleep cycle. Between stages 1-2, it’s normal to spend upwards of 60% of your time here.

“People are constantly trying to spend less time [in light sleep], but it’s actually what our body needs most. Usually people don’t like light sleep because they are having more disruptions, but there are behaviors you can do to minimize the likelihood of waking up during light sleep. I like to remind people that our body knows what it’s doing, and it takes what it needs when we fully support it in doing it’s job through our lifestyle and environment.”

Lauren Hoogs, NBC-HWC, Proper Sleep Coach

READ MORE: What Does “Normal” Sleep Look Like?