Sleep & Circadian Rhythm
If breathing is the first lever to pull to alter your physiology, sleep is the system that allows you to recover from those alterations. Every choice made during waking hours will determine what happens during this strange, paralysed, semi-conscious state.
A horizontal, unconscious creature is an easy meal, so whatever sleep is for must be valuable enough to outweigh thousands of generations of predation pressure. Research suggests that during this particularly vulnerable time of day, we undergo memory consolidation, hormonal regulation, tissue repair, and emotional processing that lets today’s traumas become tomorrow’s stories. Not only that, our brains literally rinse themselves overnight, flushing out the metabolic waste and proteins that, when allowed to accumulate, appear to be part of the Alzheimer’s Disease puzzle.
On a more immediate level, we’ve all felt the repercussions of a poor night’s sleep. Late-night blue light, too much caffeine drunk too late in the day, a stressful day… these are all common issues that leave us staring at the ceiling at 2 AM, suddenly reliving an embarrassing comment from high school, dwelling on tomorrow’s meeting, making us feel MORE anxious, which keeps us awake even longer, which then makes the next day an absolute nightmare to navigate. A single bad night of sleep can result in a self-perpetuating doom spiral of dysfunction. A few days of this and you’re a recognisably different person: irritable, foggy, emotionally reactive, making decisions you wouldn’t have made otherwise. Then there are the people who treat sleep as a weakness. The work-and-party-until-4 AM crowd, deluded about the cost they’re paying, oblivious to the fact that their judgement, performance, social skills, and lifespan are all being meaningfully shaved down. All to avoid being perceived as weak by people who are doing the same thing for the same reasons.
Which raises the obvious question: if a single bad night can turn you into an unrecognisable version of yourself, what do years of this look like?
Cardiovascular disease, type 2 diabetes, mood disorders, weight gain, increased mortality at the extremes, and accelerated neurodegeneration. Then again, we know that already, right? So, what does the medical system offer to save us from this sharp decline in healthspan? Sedation. And what is the consequence of ignoring or covering up the symptoms of a problem? That’s right, it gets worse.
Now, I don’t blame the medical industry. In fact, they are doing their absolute best with the tools they have at their disposal to prevent the bulk of us from dying prematurely. The unfortunate circumstance, which we will cover quite frequently on this site, is that we expect the medical industry (funded by the pharmaceutical industry) to do a job they aren’t trained to do. It’s like asking a plumber to build a house. It may be passable, but I expect a few nails to be abused by a pipe wrench. Without a profitable or incentive-driven way to fund healthcare, sickcare or personal responsibility is the best most of us lower-socioeconomic plebs have got. So, we’d better start learning…
Back to sleep!!!
Two systems run underneath all of this: One tracks how long you’ve been awake, and one tracks where the sun is in the sky. The interaction between them is what produces sleepiness, sleep onset, sleep architecture, and morning alertness. When sleep goes wrong, it’s almost always because one or both have been thrown out of kilter by the modern environment. Too little daylight, too much artificial light, irregular schedules, late caffeine, stress that won’t switch off, and screens broadcasting daytime signals into the night. When sleep goes right, it’s because these two systems are working together the way they were designed for.
The leverage in this is enormous, and most of it doesn’t cost anything: bright morning light, consistent timing, dim evenings, a cool, dark bedroom, caffeine discipline, movement during the day, and eating windows that stop a few hours before going to bed. None of it sells well and none of it requires a premium mattressg or a $400 supplement stack. Get the basics right, and most sleep problems resolve. Don’t get them right and no amount of optimisation will save you.
A note on what makes this section different from the popular sleep literature. Walker, Huberman, Greenfield, Asprey, and the various biohacker handbooks all have something useful to offer. Walker popularised the case for sleep mattering more than most people had been told, Huberman has been the most effective communicator of light-and-circadian principles to a general audience, and the biohacker community has recommended specific tools that can be helpful in certain contexts. But the popular discourse often grows distant from the underlying research due to sensationalism. Walker’s specific claims about sleep duration and Alzheimer’s risk have been challenged. Huberman’s protocol-level precision is personalised and informed by those he trusts (like everyone else in the world). I do my best to navigate this and base the information on what the evidence supports, citing the primary researchers whose work the practitioners are popularising, and being explicit about where the popular framing is solid versus where it’s stretching. Then again, I have fewer credentials than these experts, but less to lose.
Credit where it’s due: the section draws on primary research from Russell Foster’s group at Oxford, Charles Czeisler at Harvard, Satchin Panda at the Salk Institute, Maiken Nedergaard at Rochester, Jerome Siegel at UCLA, Till Roenneberg in Munich, Mary Carskadon at Brown, the broader chronobiology and clinical sleep medicine communities, and the 2017 Nobel laureates Hall, Rosbash, and Young whose work on the molecular clock underlies most of what we now know. Where popularisers and practitioners contributed accessible synthesis, they’re credited where their contributions appear. The full source list lives on the Resources page.
Nothing on these pages is medical advice. The sleep field includes well-evidenced interventions, contested claims, commercial products dressed up as science, and genuine clinical conditions that need professional evaluation. If sleep is significantly affecting your life, see a clinician. The framework here is meant to make you a better-informed patient, not to replace the appointment.
