The science, myths, and hard data behind the simplest health hack we all keep ignoring
By Dr. Edwin E. Spencer | AI-generated illustration, art direction by Chelsie Hall
Appeared in Cityview Magazine, Vol. 42, Issue 1 (Jan/Feb 2026)
My mantra in residency was “I’ll sleep when I die”. Sleep or admitting that you needed to sleep was a sign of weakness and that was the last thing for which you wanted to be known. It was perfectly fine to be gruff, short tempered or even a curmudgeon, but weakness was unacceptable. Therefore, I adopted the rubric of sleep when you can, eat when you can, and don’t mess with the pancreas.
It seemed logical at the time. Everyone else before me had trained this way so it must be correct. This was just a right of passage that each resident must endure in exchange for the accretion of knowledge and experience. The problem is that we all live within the gravitational pull of our own ego and it is that hubris that resonated within the echo chamber of academic institutions that perpetuated this sleep deprivation.
We now know so much more about sleep, nutrition and exercise that obfuscates this type of behavior. I believe that we empirically knew it then but chose to turn a blind eye to the obvious. It is somewhat hard to imagine that at the apogee of health care, sleep deprived and malnourished residents stumbled around like zombies bathed in monochromatic fluorescent lighting trying to learn and treat patients. However, this is not a treatise on residency training, but rather a segue into the cheapest and most ubiquitously available biohack we have to improve our health: a good night of sleep.
I have wanted to write about sleep for a while. There seems to be a growing interest in sleep trackers, sleep supplements, and sleep enhancing mattresses that appear to be primarily consumer-driven. There is good reason for this. You feel like a champ and ready to take on the world after a great night of sleep. Everyone knows this subjective feeling, but are there data to objectively quantify sleep and define “a great night of sleep”?
As it turns out, the literature is replete with data on sleep and the effects of sleep deprivation. I will try to distill this into actionable data that can be used to enhance your sleep and hopefully not put you to sleep while reading it. If you want a really deep dive into sleep science, I would suggest Matt Walker’s seminal work Why We Sleep.
The basics of sleep is that there are REM (rapid eye movement) sleep and non-REM sleep. Non-REM sleep is further broken down into light sleep in stages 1 and 2 and deep sleep in stages 3 and 4. All the stages are important despite the focus on REM sleep. A normal sleep cycle is that one progresses from stage 1 down through stage 4 deep sleep and then progresses back up through the stages in reverse order to get to REM sleep and then a mild awakening occurs and the process begins again.
A normal sleep cycle is around 90 minutes, but this varies with each person. The cycles are not uniform throughout the night. The first half of sleep has more deep sleep while the latter half is where we pick up more REM. Deep sleep is where we get large boosts of growth hormone secretion; REM sleep we get more testosterone production.
SEDATION is not SLEEP
What happens during each sleep stage and its importance is fascinating. Stage 2 seems to be most important for motor memory. Acquired motor skills are replayed during this stage to cement them so that they become second nature to us or “muscle memory.” Deep sleep is most important for declarative memory. Facts encountered throughout the day are stored into short term memory in the hippocampus and then transferred to the cortex for permanent storage. REM sleep is where the brain is most active at night (except for the logic centers). The brain will grab data from all kinds of places and put them together which can create some irrational dreams but also stimulate remarkable creativity. REM sleep is also critical for emotional processing. Luckily, we are paralyzed in REM sleep (except for eye and ear muscles) so that we can not act out our dreams. Have you ever been in a dream and tried to run from something and can’t move? This paralysis of voluntary motor control is why.
Much of what we know about sleep has been acquired through sleep deprivation studies. One of the more brutal studies was on complete sleep deprivation in rats who made it about 15 days before dying. Human experiments on milder forms of sleep deprivation have yielded some disconcerting results as well. Just five nights in a row of being under slept (five hours per night) will cause your blood glucose and insulin to rise and become clinically insulin
resistant. You will be 3 times more likely to get the cold or flu due to the negative effects on the immune system. In addition, two of the main hormones that control hunger (ghrelin) and satiety (leptin) become out of balance making you hungrier. Another very important hormone for men and women is testosterone which decreases to the point of someone 10 years older than your actual age when you are under slept. Not only is our metabolic health affected with being under slept, your motor function decreases as well. A study on basketball players demonstrated that all metrics including vertical jump, speed, and shot percentage all decreased with just five nights of six hours of sleep. I almost forgot to mention the glymphatic system in the brain. It is the brain’s lymphatic system that clears the byproducts of the day’s activity, and this happens almost exclusively during sleep.
Enough with the scare tactics. We all know we need good sleep. So, what defines that? First is quantity. We need between seven and nine hours of sleep. We also need quality sleep which is minimally fragmented. Sleep trackers can help determine your sleep efficiency (how fragmented your sleep is) and time in each stage. Fragmentation occurs when we awaken. Mild awakenings are normal but at least 85% of your sleep should be non-fragmented. We should also shoot for one-and-a-half hours each of deep and REM sleep. Sleep trackers do a fairly good job determining your sleep metrics using accelerometers to measure motion, thermometers to measure temperature, and infrared to measure heart rate and variability. Assumptions are then made from those data to determine your stage of sleep. One needs to determine the accuracy of their preferred tracker by researching the fidelity of the tracker to electrosomnography.
How do we get great sleep? Environment and consistency are key. Go to bed and wake up close to the same time every day. Avoid blue light like on computers and phone screens. The bed is for sleep and sex, not for working on the computer. I’ve not seen any data on the effect of sex on sleep but anecdotally it works well and I’m a huge fan. Try reading a good ole fashion book instead of the phone. Avoid alcohol and THC. Both are sedatives, but sedation is not sleep. Both significantly impair REM sleep and alcohol markedly fragments your sleep. Avoid bright lights and make the bedroom cold and dark. I like to sleep at 68 degrees if possible.
Almost 70% of Americans report that they have difficulty sleeping one or more nights per week and 30% report bouts of insomnia. Creating
a calm, dark and cold sleeping environment can help foster good sleep. A hot sauna or shower a couple hours before bed can actually lower your core body temperature at bedtime and help induce sleep. Some folks like to drink chamomile tea which does work. There are many other sleep supplements that are too numerous to expound upon here, but if interested you could go to my website spencerhealthmd.com for a deeper dive on what might be right for you.
Sleep should be viewed as an investment in your health and future. I mean, honestly, if I told you that
I could give you a pill that lowered your blood pressure and blood glucose, cleaned your brain of toxins and debris, made you smarter and more emotionally stable, and increased your growth hormone and testosterone, everyone would stand in line for it. Fortunately, all these benefits come with good sleep, but we have to be intentional to create a schedule and environment that allows us to experience a glorious night of sleep.
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