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Happy New Year Everyone! Here is another edition of the monthly "Amuse-Bouche" series. Just like a morsel compliments of the chef, these small but critical scientific bites are intended to stimulate thinking about health. I hope you enjoy them. The one and only free lunch Unlike exercise and meal prep (time and planning), medications (money/complexity/side-effects), sleeping eight hours a night is the rare intervention that costs nothing. And yet we treat it as negotiable. We’ll wake at 5 a.m. for a workout but don’t protect bedtime. We spend $200 on organic groceries but drink coffee at 4 p.m. and lay awake at night. We stare at screens while our brain is trying to initiate sleep. Meanwhile we’re tracking macros, wearing a glucose monitor, poring over numbers - while quietly sleeping 5–6 hours and treating that as the fixed cost of adult life. Myself included. I have had more phases in the last 15 years where I have had my sleep routine dialed in, but not for the greater part of my life. The irony is almost cruel: a very powerful, free intervention is in our own bed, and we dismiss it while investing heavily everywhere else. When things calm down / I lose weight / finish this project / get notes done, then I’ll sleep. Sadly, sleep deprivation and sleep fragmentation don’t allow us to get to our goals effectively or sometimes, at all. In plain language Every mammal studied to date sleeps, and sleep (or sleep-like states) is also observed across birds—suggesting sleep is a biological necessity, not a lifestyle preference. In humans, sleep is a reversible state of reduced responsiveness and characteristic brain activity: we’re typically lying down, disconnected from the external environment, yet still arousable (we can be awakened by meaningful stimuli). Distinct from fainting for instance, where we have reduced responsiveness, but the characteristic stages of sleep are absent in our brain. It is not “shutdown.” It is an actively regulated period during which the brain and body run coordinated programs - memory processing, metabolic regulation, immune modulation, and other restorative functions - that are difficult or impossible to perform efficiently while awake. One of the clearest biochemical signals of “sleep pressure” is adenosine. During wakefulness, adenosine accumulates in the brain as a byproduct of neuronal activity and energy use; rising adenosine contributes to increasing sleepiness and reduced alertness. Caffeine works largely by blocking adenosine receptors, which is why it can temporarily mask sleepiness without replacing sleep. During sleep - especially consolidated, high-quality sleep - adenosine signaling and sleep pressure decrease, restoring the brain’s capacity for sustained wakefulness. With sleep restriction, that sleep pressure does not fully reset. People often feel they have “adapted,” but performance impairment and physiologic stress accumulate across consecutive days - consistent with a rising sleep debt. And sleep is not optional in the literal sense: sustained inability to sleep is incompatible with life; rare neurological diseases that progressively abolish sleep (for example, fatal familial insomnia) are ultimately fatal. What these patients die of is often septicemia. Their skin and gut lining break down, the immune system fails. Normal sleep cycles have an architecture During NREM - especially stage N2 - the brain produces sleep spindles [brief bursts of brain-wave activity] that help stabilize sleep and support learning and memory processing. During REM we process and stabilize our emotions. Deep sleep is front-loaded - it shows up most in the first part of the night. So, when bedtime gets pushed later, we disproportionately lose deep sleep. And deep sleep is where a lot of the anti-aging machinery is active. Many studies have shown that people who learn a skill or information and come back after a night of sleep retain far more than those who don’t get a full night of rest. Figure of 8 That is the magic number. For some a little less like 7+ and for other adults a tad bit more, 9+. When sleep is short, delayed, or fragmented, we walk around with slower processing speed, worse attention and working memory, word-finding difficulty, and poorer judgment and reaction time. We catch more colds. We don’t build immunity after vaccines as effectively. But we feel fine. The illusion is convincing: we feel we’ve adapted to this baseline while we’re objectively worse (multiple tests and research studies have proven this). Long-term, this isn’t just about feeling foggy. Loss of slow-wave sleep has been associated with higher risk of incident dementia, and mechanistically, deep sleep appears to support the brain’s “waste clearance” activity during sleep. “Make up” sleep does not exist. Categories of sleep disorders Insomnia Disorders Sleep-Related Breathing Disorders (SRBD)
(includes obstructive sleep apnea, central sleep apnea, hypoventilation, upper airway resistance syndrome, etc.) Central Disorders of Hypersomnolence
(e.g., narcolepsy, idiopathic hypersomnia, etc.) Circadian Rhythm Sleep - Wake Disorders
(e.g., delayed, advanced, irregular, non-24-hour sleep-wake patterns) Parasomnias
(e.g., sleepwalking, REM sleep behavior disorder, night terrors, confusional arousals) Sleep-Related Movement Disorders
(e.g., restless legs syndrome, periodic limb movement disorder, bruxism) Other Sleep Disorders
(a category for less common or not fully specified disorders)
Each of those categories contains multiple individual diagnoses. See a sleep specialist! Why sleep problems change our body composition, appetite, and aging trajectory Growth hormone (GH) [less repair/rebuild signal/anti-aging]
GH is secreted in pulses, with a key pulse shortly after sleep onset, in association with the first episode of deep slow-wave sleep. Delay bedtime or fragment the first part of the night, and we blunt that early repair window. Testosterone (men) [less muscle, libido, drive, bone, mood]
Short sleep or sleep apnea lower testosterone. Clinically, low testosterone looks like loss of muscle and strength, easier fat gain (especially central), lower energy/drive, lower libido/ED, depression or flattened mood, and higher bone-loss. Estrogen + progesterone (women) [less sleep stability, airway tone, mood]
Estrogen helps maintain airway muscle tone. After estrogen production declines, the airway can become more collapsible—especially during REM, when the body is naturally paralyzed. Normal or underweight women can be at risk too. Insomnia, non-restorative sleep, awakenings, and apnea often increase, and the cluster—fatigue, brain fog, mood volatility, weight gain—gets labeled as “just menopause,” when breathing disruption maybe the culprit. Cortisol [more stress]
With insufficient sleep, the stress system runs overtime and at the wrong times. Blood pressure, blood sugar, and pulse run higher. Insulin sensitivity [how well we handle glucose]
Sleep restriction reduces insulin sensitivity. Healthy volunteers who are sleep deprived for one night can develop blood sugar numbers that qualify as pre-diabetes. That’s why the “perfect diet” can feel like it stops working when sleep is short or broken. Leptin [satiety: “I’m full”] and Ghrelin [hunger: “I want more”]
Less than 8 hours of sleep is associated with lower leptin, higher ghrelin, and increased hunger/appetite. This is the biology behind cravings and “why is my appetite feral today?” Melatonin [sleep timing signal]
Late light and screens can delay melatonin onset - making it harder to fall asleep earlier even when we’re exhausted. Sleep fragmentation: As harmful as apnea Most of us have heard of OSA [obstructive sleep apnea]. Some people don’t have classic apnea, but they have UARS [upper airway resistance syndrome] and RERAs [respiratory effort–related arousals]: repeated increases in airway resistance that trigger brief arousals and fragment sleep. This can occur in very thin individuals. But sleep fragmentation - often without remembering - isn’t benign: it is associated with long-term all-cause and cardiovascular mortality, similar to sleep apnea. Bruxism [clenching/grinding] causes sleep fragmentation and can be a consequence of upper airway resistance. Bruxism causes micro-arousals and stress hormone production that impacts all organs, just like frank apnea. If crowding or shifting of teeth is present, before we jump to braces, it’s worth asking why the teeth are behaving that way. The answer can lie in our nose, mouth, and throat - our airway. If we don’t treat the underlying cause, the bruxism continues, and we not only have to pay thousands of dollars again, but suffer it’s long-term cardiovascular consequences. Concrete examples of the hidden costs of sleep problems (the ones we mislabel as “resistant”) the person who can’t lose weight despite perfect adherence the person on 2-3 BP medications but numbers won’t drop adequately the anxiety patient cycling through medications the patient with insomnia who is desperate to sleep the patient who “should not” be prediabetic
Dipping [the normal 10-20% drop in blood pressure during sleep] is a quiet benefit of stable sleep. Fragmented sleep and sleep-disordered breathing can erase dipping (“non-dipping”), keeping blood pressure elevated at night and raising cardiovascular risk. What it costs us: personally, at work, and nationally The national costs are enormous: insufficient sleep is estimated to cost the U.S. economy hundreds of billions per year. Then there’s safety - drowsy driving causes accidents and lost lives. The personal costs are quieter: worse cognition, worse metabolic health, worse mood regulation, worse sexual function, higher accident risk, and a body that ages faster than it should. All this impacts our relationships, ability to take care of ourselves and exercise, play with our kids and spend time with friends, success at work, money spent treating other related health problems. This can shave 10 to 15 years off our lives. Many of us assume our sleep is “fine” or unfixable. Often, it’s neither. A sleep evaluation can be less invasive than tests we do routinely, and treating the right problem can be transformative. It can be as simple as wearing a ring or a watch to bed. Signals can be subtle: low energy/fatigue waking unrefreshed despite enough time in bed frequent awakenings (or light, easily disrupted sleep) memory problems morning headaches, dry mouth, sore throat nocturia [waking to urinate], especially in women, or if persistent/worsening bruxism, jaw/neck tightness on waking brain fog, irritability, afternoon crash reduced libido/sexual function plus fatigue acid reflux
Medical conditions that should push us to ask for a sleep workup (even if no one offers)
Atrial fibrillation, difficult to control hypertension or needing multiple medications, heart failure, heart attacks, strokes, type 2 diabetes/obesity/fatty liver, weight gain, difficulty losing weight, chronic pain syndromes, treatment-resistant depression/anxiety/insomnia
Enter night, exit light protect a consistent bedtime (deep sleep happens early; sleep late and we lose a large part of it) morning bright light, evening dim light earlier caffeine cutoff - none after noon alcohol isn’t useful: it sedates but fragments sleep treat nasal obstruction/allergies consider CBT-I [cognitive behavioral therapy for insomnia] evaluate for sleep-disordered breathing (including fragmentation/UARS patterns, not just apnea)
Sleep is an overlooked foundational intervention while we chase everything else. If we don’t plug this leak, we can keep bailing - more meds, more tracking, more supplements - and still feel like we’re losing. When we get sleep right, the rest of the plan finally has a platform to run on. Off to never-never land. Consider forwarding this to a loved one-it may help someone you care about. Want to sign up for your own monthly Amuse-bouche op-ed series, in case this was forwarded to you? Go here. Want to check out prior editions of Amuse-bouche? Go here. Medical disclaimer: This article is education, not medical advice. Please contact your medical provider for advice. Photo: Me
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