A Circadian Revolution

This piece originally appeared in The Source: The Anti-Optimisation Issue, Healf's print magazine.

You can sense a shift in the way people talk — and obsess — about it. The questions filling TikTok feeds, doctors’ appointments, and dinner tables all point in the same direction: how to sleep better, deeper, longer, more efficiently.

With each new study and scientific breakthrough, it’s becoming increasingly clear that sleep is foundational to every aspect of wellbeing, from metabolic health and hormone balance to cognitive function and emotional resilience. It’s an active state, as essential as eating or breathing, that allows our bodies to regulate, repair, and recalibrate. “We’re seeing a real shift in how people think about sleep,” says Dr. Frankie Jackson-Spence, MBChB, MRCP, a medical doctor. “Patients aren’t just asking how much they need, but how to improve quality, consistency, and timing.” 

Just over half of people rank sleep as the most important behaviour for living a long, healthy life, according to ResMed’s 2026 Global Sleep Survey. Yet that knowledge doesn’t necessarily translate to better rest. In the UK, almost one in five adults aren’t getting enough sleep, Mental Health UK reports, while the NHS estimates that insomnia affects around one in three. In fact, our collective sleep issues have become so troublesome that they’ve given rise to an entire industry that promises to deliver deeper, more efficient rest through endless products, protocols, and tools. Still, sometimes it seems like the more we try to engineer sleep, the harder it is to access. 

The strange thing is, the fundamentals of good sleep haven’t changed for millennia — it’s the world around them that has. Our days extend well past sunset, we get less natural light, and we’re constantly stimulated by our devices. All of this wreaks havoc on our circadian rhythm, that key clock behind our internal biology. And if sleep sits at the centre of everything, it’s crucial to get it right. 

The Biology Of Sleep

The longevity industry presents all kinds of hacks and products designed to help support and optimise your health, but one of the most effective interventions is the thing we already do for seven to nine hours every day: sleep. This one behaviour affects a huge range of essential biological factors, from inflammation levels to brain health, metabolic function, and immune resilience.

While it seems simple, sleep is actually a highly coordinated biological process. As evening approaches, your brain begins to release melatonin, the hormone that signals it’s time to wind down, while cortisol, which drives alertness, starts to fall. Your core body temperature drops, heart rate slows, and neural activity shifts, moving your body into a state that supports repair rather than performance. Throughout the night, your brain then cycles through different stages of sleep that each play a distinct role in your overall wellbeing. “The brain clears waste, consolidates memories, and regulates stress hormones. When that process is repeatedly disrupted, it has serious consequences,” says Dr. Lafina Diamandis, MBBS, MRCGP, a GP and lifestyle medicine doctor.

As humans, we feel the impact of poor sleep almost immediately: we think slower, find it difficult to stay focused, have a shorter fuse. What’s less obvious is how quickly those short-term effects compound to affect our long-term health. Over time, consistently poor sleep has been linked to a higher risk of depression, anxiety, and cognitive decline, with growing evidence connecting it to neurodegenerative conditions such as dementia.

On the flip side, consistent, good-quality sleep improves memory, decision-making, and attention, and changes how the brain’s networks communicate. Deep sleep, in particular, carries disproportionate weight because it is during this stage that many of your body’s most critical repair and clearance processes are most active. “Slow-wave sleep is when the brain’s waste clearance system works most effectively,” Dr. Diamandis says. “It helps remove proteins like amyloid-beta and tau, which are linked to Alzheimer’s disease.”

Sleep also has a significant impact on cardiovascular health. Short sleep duration is associated with higher rates of heart disease, high blood pressure, insulin resistance, and type 2 diabetes. Our immune systems follow a similar pattern: “People who are not sleeping well often feel run down and are more likely to pick up infections,” says Dr. Diamandis. Large-scale studies have consistently linked inadequate sleep with increased inflammation, impaired glucose regulation, and a higher long-term risk of chronic disease, reinforcing how closely sleep is tied to overall health.

The challenge is that none of these effects are obvious after one bad night’s sleep. Our bodies appear to adapt, compensate, and continue on. But that short-term resilience can be misleading. The reality is, the negative effects of poor sleep accumulate gradually, only showing up months, years, or even decades later.

Even when we get “enough” sleep, irregular timing can create its own strain on your body. When you go to bed at different times, it creates a mild jet lag effect, hurting your sleep quality. “People often sleep poorly during the week and try to catch up at the weekend, but sleep doesn’t work like that,” says Dr. Diamandis. “You can’t repay the debt later and expect the same benefits.”

The takeaway here is pretty simple. The benefits of consistent, good sleep build slowly but surely. “Even if you can’t feel the changes directly, they’re still happening,” Dr. Jackson-Spence says.

A Modern Problem

Clearly, the question is no longer why sleep matters, but why it’s become so difficult to get right — and how to fix it. The answer lies less in biology and more in how we live today. Modern life isn’t designed with sleep in mind, and that wreaks havoc on our circadian rhythm. Yet, even if our lives are out of sync with the natural world, our biology is still governed by it. “All of our cells run on an approximately 24-hour rhythm,” says Dr. Sophie Bostock, PhD, MSc, a sleep scientist. “There is a master clock in the brain, but every cell has its own molecular clock. When those systems are aligned, the body runs efficiently. When they fall out of sync, it creates stress on the body.” 

Our response to this problem hasn’t necessarily been to tune back into these natural rhythms. Instead, we’ve introduced and experimented with devices that track every movement, supplements designed to fine-tune recovery, and carefully constructed routines aimed at engineering the perfect sleeping conditions. And while this can be helpful for some, it can also add friction for others. Sleep quickly becomes something people try to optimise, which creates pressure around bedtimes and anxiety about “getting it right”. “Sometimes people become too focused on doing everything perfectly,” says Dr. Bostock. “Sleep varies from night to night, and that is normal.”

The truth is, the harder we try to control sleep, the more elusive it can feel. Instead, we need to try to understand which signals actually matter, and how to work with our bodies, rather than against them.

Seeking Sleep

One of the most effective approaches to decoding sleep is actually a pretty straightforward one: focus on quality. “It’s not helpful to tell people to ‘just get more sleep’,” says Dr. Jackson-Spence. “Most people already know that. If you can’t increase the number of hours immediately, focus on improving sleep quality.”

To help achieve this, Dr. Jackson-Spence encourages people to try to go to bed and wake up at roughly the same time each day. “Even a one-hour window can make a difference,” she says. From there, focus on the cues your body relies on to regulate when we feel alert and when we feel ready to sleep. Light is one of the most influential ones we have. “Morning daylight helps anchor your circadian rhythm,” she says. “In the evening, reducing light and stimulation helps signal that it is time to wind down.”

Your environment also shapes how easily sleep comes. “The body needs to drop its core temperature slightly to initiate sleep,” Dr. Jackson-Spence adds. “A cooler room, breathable fabrics, and good ventilation all help.” A simple pre-bed ritual can also help the brain anticipate sleep, whether that’s reading, stretching, or dimming the lights. In many ways, these habits mirror what sleep looked like long ago: slower evenings, fewer stimulants, and a clearer transition between day and night.

There is also value in knowing when to stop trying to force sleep. “If you’re lying in bed for more than 15 to 20 minutes and feeling frustrated, get up,” says Dr. Bostock. “No one falls asleep faster by trying harder.” Instead, move into a low-lit space and do something quiet and undemanding, like reading or listening to something familiar, before returning to bed once you feel sleepy again.

Taken together, these habits create the conditions that sleep depends on. It isn’t something to force into place, but a process that occurs more seamlessly when the signals around it remain steady. The aim isn’t perfection, but finding a rhythm — one the body can recognise and return to each night.

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