We don’t get enough sleep, and fixing this problem is paramount. As scientists have unraveled the mysteries of our brains and how and why we sleep, studies have shown that getting enough sleep is arguably the most important thing we can do to improve our physical and mental health to live better, longer.
In Part One, we explored what sleep is, why we need it, and the dangers of poor sleep relative to illness. In this next story, we’ll share insights from sleep scientist Matthew Walker, Ph.D. on how being underslept impacts metabolism and weight, performance, and fertility and genetics, explored in detail in his seminal book Why We Sleep and podcast The Drive, hosted by Peter Attia, MD (resource notes below).
We’ll also note how caffeine, alcohol, THC, and CBD impact sleep, and share tips on how to get better quality shuteye from CANOPY’s resident Registered Dietician Nutritionist Brittany Kearney. Brittany will give a series of Longevity talks at CANOPY locations in the coming months. Join us for her next event, Longevity 101, at Menlo Park on 03.30.23.
Effects of Poor Sleep: Metabolism and Weight
Sleep is a single factor with impacts ranging from complex cognitive issues, like decision-making, to metabolic shifts. A lack of sleep affects the regulation of what we choose to eat with regard to energy density, the volume of food ingested, and how our body manages our blood sugar. When we’re underslept, the hormone leptin, which signals satiety, drops. In contrast, ghrelin, which signals hunger, is ramped up, leading us to eat more.
Short-slept people are also more likely to reach for starchy carbohydrates and simple sugars–comfort foods like pizza, cookies, and ice cream–over lean protein and leafy greens. In conversation on The Drive, Walker explains that when sleep-deprived subjects were placed in a brain scanner and shown different food images, observing scientists noted that the prefrontal cortex, the part of the brain that keeps impulses in check, was not functioning correctly. In contrast, more primitive areas of the brain, particularly the amygdala, remained highly active in its hedonic response to desirable foods.
As a result, most people who were short-slept in studies by two or three hours consumed around 300 more calories a day than when they were well-rested.
Being underslept not only influences which foods we choose and how much we eat, but how our bodies convert it to energy. Subjects restricted to four hours of sleep a night for two weeks suffered a 50 percent reduction in their ability to put glucose into their muscles, retaining it in their bloodstream–health professionals looking at their results would conclude they were pre-diabetic, even though their numbers were normal before the study.
When we get enough sleep, beta cells in the pancreas sense a spike in blood sugar and release insulin, which instructs the cells of the body to reach out and absorb glucose from the blood. When the body is underslept, our beta cells become insensitive to blood sugar spikes, and the body stops releasing sufficient insulin for the food consumed. This effect is compounded by the fact that the cells of the body become insensitive to insulin and subsequently remove less sugar from the bloodstream, which is why diabetes rates are higher in people who have untreated sleep apnea than in otherwise healthy populations.
Effects of Poor Sleep: Performance
When people are sleep deprived, we’re far less likely to be active and substantially less motivated to exert ourselves when we are physically active. In studies, when a healthy person is limited to six hours of sleep, the time before they become physically exhausted is reduced by 30 percent–Walker uses the analogy of a person who has successfully trained to complete a 10K but who will fail at the 7K mark if they only have six hours of sleep. When we sleep well, we work harder, both physically and mentally, and this is a trait that translates to the workplace.
In studies, Walker noted that employees who sleep six hours or fewer select less challenging problems, for instance, answering emails rather than tackling hard project work. When subjects do engage in problem-solving tasks, they produce fewer creative solutions to those problems–a finding that’s highly detrimental for startups and entrepreneurial organizations where creativity and ingenuity drive business. Walker also said that underslept employees working in groups shirk tasks and rely on their teammates to do the work, which is bad for both productivity and morale.
The study also found that the less sleep an employee had, the more unethical they became–they would increasingly falsify data, reports, and reimbursement claims–which refers back to the impeded function of the prefrontal cortex and an uptick in impulsivity. Another study looked at how staff members viewed their sleep-deprived CEO. Day to day, the less sleep business leaders had, the less inspiring and charismatic employees found them, even though the team did not know a sleep experiment was being conducted.
Effects of Poor Sleep: Fertility and Genetics
Scientists observing female study subjects who slept five to six hours documented a 20 percent drop in follicle-stimulating hormone (FSH) and an increase in abnormal menstrual cycles by 30 percent, both of which have a critical impact on a woman’s ability to conceive. In underslept men, testosterone dropped to the level of someone 10 years their senior. They also produced fewer sperm, a higher proportion of which were unviable or exhibited diminished motility. Both factors negatively impact wellness and fertility. If both partners in a couple trying to conceive are operating on six hours of sleep, it’s less likely they’ll be successful.
From an evolutionary perspective, being less fertile when we’re sleep deprived makes sense–a lack of sleep would have signaled danger and hardship, both suboptimal for procreation–but in modern society, this can be devastating for people who work long hours but are otherwise in a good situation.
Limiting sleep to six hours in a healthy adult will result in substantial changes in their gene activity profile relative to when those same individuals were getting eight hours of sleep. Studies in this area led to two significant findings. Of the 20,000 genes in our genome, scientists found that 711 genes had their activity distorted due to insufficient sleep over seven days–a substantial epigenetic change of three percent of the genome. Around half of those genes were upregulated, such as genes associated with tumor promotion, stress, and long-term chronic inflammation.
How Caffeine, Alcohol, THC, and CBD Impact Sleep
Alcohol is a sedative that acts on the same class of receptors as many sleeping pills. When we indulge in a boozy drink before bed, we’re sedating our brain to lose consciousness quicker, not falling asleep more quickly, and we’re more likely to wake up during the night, even though we might not remember wakeful episodes. Alcohol can raise our body temperature and heart rate, negatively impacting our ability to sleep, and also block REM sleep, when we dream, causing us to wake the following day feeling unrefreshed and unrestored.
Enter caffeine, which blocks the sleep pressure signal adenosine. Humans are usually at their most alert between 10 a.m. and 11 a.m., and if this is when you reach for the French press, you’re likely underslept. Caffeine has a half-life of around six hours and a quarter-life of 12 hours. While some people are less sensitive to caffeine and might not experience a deleterious effect on their ability to get some shuteye following a post-dinner espresso, for most people, a quarter of the caffeine consumed in a cup of coffee at midday continues to affect their brain at midnight. In a study, Walker found that giving someone a standard 200-milligram dose of caffeine in the evening resulted in a 20 percent reduction in deep sleep: the equivalent of that individual being 20 or 30 years older.
Acute use of THC seems to decrease sleep latency, i.e., the amount of time it takes someone to fall asleep, but THC, like alcohol, blocks REM sleep with the same effect. The increased tolerance to THC associated with chronic use means that individuals need to use more to get the same reduction in sleep onset time, essentially becoming more dependent on THC to sleep–Walker’s studies found that people who stopped using THC as a sleep aid after long periods experienced a rebound in insomnia.
While Walker admits that there’s insufficient data around how CBD impacts sleep, indications from the few non-placebo controlled trials conducted suggest that CBD does help people to fall asleep faster without negatively impacting REM sleep–perhaps because of its thermoregulation qualities and anxiolytic benefits–and that subjects didn’t develop dependency or insomnia if they stopped taking it. Conversely, there are suggestions that CBD at a specific dose is wake-promoting, so there’s likely a sweet spot concerning optimal CBD dose concentration for improved sleep.
How to Encourage Better Sleep
Up to 10 million American adults reportedly take some form of sleep aid each month, not counting over-the-counter options like the allergy medication Benadryl, which many people misappropriate because it causes drowsiness. Although Walker’s studies seem to show that the impacts of poor sleep aren’t reversible–you can’t binge sleep to repair damage caused by a previous period of sleep deprivation–it’s never a waste of time to start sleeping better to help course-correct our risk of dementia and other health problems.
Tips from Brittany Kearney, CANOPY’s resident Registered Dietician Nutritionist, on ways to sleep better:
- Get bright light exposure in the first half of the day, and limit your light exposure in the second half. Try taking a walk before breakfast–or at least sit outside or by an open window–for 10 to 15 minutes in the morning to allow bright sunlight to drop your melatonin and stimulate growth and metabolism hormones. After sunset, avoid overhead lighting and bright screens by using bedside lamps, apps that block blue light, or night mode on devices at least one hour before bed.
- Your body temperature must drop at least two degrees Fahrenheit before you can fall asleep. Try a hot shower or bath 30-60 minutes before bed to help your body cool itself more efficiently. You can also try cooling mattress pads like the Slumber Cloud or EightSleep.
- Melatonin can help drop body temperature, but it’s only a starting signal–it doesn’t help to improve the quality of sleep or help you stay asleep. Melatonin has been shown to only increase sleep by roughly three minutes in healthy younger adults. Still, it can help people over 65 because the pineal gland, part of our endocrine system which secretes the hormone melatonin, can become calcified, so melatonin production in older people might remain steady over time instead of peaking. Melatonin starts rising at dusk and peaks one or two hours later, around when we should be going to sleep.
- Avoid alcohol four to five hours before sleep. Alcohol is a sedative, and while it might feel like it helps you fall asleep, it just makes you lose consciousness quicker. Alcohol fragments your sleep, activates the autonomic nervous system, significantly reduces REM sleep, and induces a reduction in testosterone and a more than 50 percent drop in growth hormone.
- Stop drinking caffeine eight to 10 hours before sleep. Caffeine can affect the level of deep sleep (a reduction of up to 30 percent), which can age you by 10 to 12 years.
- Magnesium threonate is a popular supplement taken to improve sleep quality. While it passes the blood-brain barrier effectively, research on magnesium, in general, is uncompelling. If you are Magnesium-deficient and take it to restore your levels to normal, it may help improve sleep.
- Studies show tart cherry juice reduces the time we spend awake at night for over an hour and increases sleep time by 30 to 80 minutes.
- Kiwi skin can help you fall asleep faster, stay asleep longer, and increase total sleep.
- Naps of 20 to 90 minutes are beneficial for cardiovascular health, blood pressure, maintaining cortisol levels of cortisol, learning, memory, and emotional regulation. Naps should be taken six to seven hours before you want to fall asleep at night and be 20 to 25 minutes in duration to ensure you feel less groggy after you wake up. Naps reduce adenosine buildup–the sleepiness signal–so if you struggle with sleep at night, try avoiding napping altogether.
About Brittany Kearney
Registered Dietician Nutritionist
After graduating with a Bachelor of Science in Genetics from UC Davis, Brittany completed a Dietetic Internship through Napa State Hospital and Stanford’s Genetics and Genomics Professional Certificate Program. She received functional medicine training through IFM and specializes in nutrigenomics and epigenetics. Brittany offers insights into how we can live better and longer through her Longevity Series talks at CANOPY.
Join us for Brittany’s next Longevity 101 event at Menlo Park on 03.30.23.
Resources for this story:
- Why We Sleep, by Matthew Walker, Ph.D., professor of neuroscience and psychology at the University of California Berkeley and the founder and director of the Center for Human Sleep Science. Walker is also a sleep scientist at Google, supporting the scientific exploration of sleep and its impact on health and disease.
- Episodes dedicated to sleep on The Drive, hosted by Peter Attia, MD, the founder of medical practice Early Medical, which applies principles of Medicine 3.0 to patients aiming to lengthen and improve their lifespan.