
Fountain of Youth: The Science of Fasting
How intermittent fasting can slow aging and boost longevity
For those who travel far and arrive ruined.
Jet lag isn't just an inconvenience. It's a full-blown neurological hijacking — a mutiny of circadian rhythm, cortisol, and dopamine. One moment you're upright and ordering espresso in Rome; the next, you're staring at a hotel ceiling in full REM denial while your internal clock insists it's breakfast in Tokyo.
This is not merely fatigue. This is what the Harvard Medical School calls a “chronobiological disruption” — a deeply inconvenient term for a very specific kind of human unraveling. And it happens because your body's master clock (the suprachiasmatic nucleus, tucked in your hypothalamus) doesn't like surprises.
Fortunately, there are ways to overcome it — rituals, techniques, molecular hacks. And like all good strategies, they are rooted in rhythm, light, discipline, and a touch of suffering. Here are five.
Your circadian rhythm is set by light, not intention. The photoreceptors in your eyes — particularly the melanopsin-containing retinal ganglion cells — respond most strongly to blue light around 460–480nm. This wavelength reaches the SCN (suprachiasmatic nucleus), your brain's master timekeeper, and tells your body: It's day. Get it together.
When you cross time zones, your internal clock doesn't reset on arrival. It keeps ticking according to where you were. Even if it's 8AM in Florence, your brain may still believe it's 2AM in Chicago. That mismatch is what causes the confusion, fog, insomnia, and existential bewilderment known as jet lag.
The fix? Light. But not just any light — timed light.
For eastward travel (where you're jumping ahead in time, like New York to Paris): expose yourself to bright natural light early in the morning at your destination. This pulls your internal clock forward. Conversely, avoid bright light in the late afternoon and evening.
For westward travel (like London to Los Angeles): do the opposite. Avoid early morning light and aim for afternoon and early evening light exposure. This helps push your body clock later, aligning it with the new schedule.
Natural sunlight is best — it delivers full-spectrum wavelengths that indoor lighting can't match. But if you're arriving in winter or staying indoors, a 10,000 lux light box can do in a pinch.
Apps like Timeshifter or downloadable chronotherapy charts can calculate your ideal light windows based on travel direction, time zones crossed, and departure/arrival times. It feels nerdy at first — but so does sitting in a café at 4AM hallucinating about oatmeal.
Bonus tip: bring a pair of orange or red-tinted blue-light-blocking glasses for flights and hotel evenings. They don't make you look cool. But neither does sobbing into a croissant while Googling “how to sleep in France.”
Let's get this straight: melatonin is not a sedative. It doesn't knock you out. It doesn't create sleep where there is none. It's not a tiny pill full of dreams. What melatonin actually does is signal to your body that night is falling. It whispers to your circadian machinery: start winding down.
Your pineal gland naturally produces melatonin in response to darkness — particularly the absence of blue light. In a properly aligned system, levels begin rising in the evening, peak in the middle of the night, and taper off by morning. But after a long-haul flight across time zones, this rhythm is no longer in sync with your new environment.
That's where supplementation can help — but only if you take it at the right time.
For most people, a small dose (0.5mg to 3mg) taken 2 to 3 hours before the intended bedtime in your destination is optimal. That timing helps shift the body's internal clock toward local time, nudging you gently into rhythm.
Taking it at the wrong time? That can make things worse — reinforcing the old time zone and confusing your biological systems. Taking too much? That often leads to grogginess, vivid dreams, or a melatonin hangover.
The key is precision.
Flying east? Take melatonin in the early local evening for the first few nights.
Flying west? You might not need it — but if you do, take it later in the evening to help solidify your delayed bedtime.
Also important: don't take it too early on the flight. Many people pop a melatonin tablet the moment the wheels leave the runway. Don't. That just tells your body to prepare for sleep in the middle of what could be its natural daytime. Think in destination time — not departure time.
And remember: melatonin isn't a sleeping pill. It's a signal. It doesn't override light exposure, caffeine, stress, or temperature cues. It works best when combined with other circadian-alignment strategies.
So yes — take it at the right time. Then let your biology do the rest.
Your body isn't just tracking light — it's also tracking heat. Core body temperature follows a circadian rhythm: it begins to drop a few hours before bedtime and reaches its lowest point in the early morning, helping to initiate and maintain deep, restorative sleep. Jet lag throws this rhythm off, which is why you might find yourself wide awake at 3AM or crashing hard at noon.
The strategy? Mimic the temperature cues your body expects.
Start with a warm bath or shower about 60–90 minutes before bed. This triggers surface vasodilation — your blood moves toward the skin, which causes heat to escape more efficiently afterward. That drop in core temperature signals to your body: it's time to sleep.
Once you're in bed, make the room cold — ideally between 60–67°F (15–19°C). This range has been confirmed by both the NIH and sleep researchers as optimal for most adults. It helps reduce nighttime awakenings, improve REM quality, and shorten sleep onset latency. Too hot, and your body can't thermoregulate efficiently. Too cold, and you might wake up shivering. But that 60–67 sweet spot? That's where your body sinks into the deeper cycles.
One study published in Sleep Medicine Reviews found that even subtle increases in skin temperature (as little as 0.4°C) significantly impacted the ability to fall and stay asleep. The same review confirmed that warm ambient conditions — anything above 75°F (24°C) — led to longer sleep latency and fragmented sleep, especially in summer and among older adults.
Morning strategy? Reverse the process.
As soon as you wake up in your new time zone, stimulate alertness with cold: splash water on your face, open a window, or take a brisk walk. If you're committed, do a short cold shower or plunge. This raises core body temperature and sends a loud, clear signal to your hypothalamus that the day has begun — regardless of what your melatonin cycle thinks.
Bonus cue: meal timing.
Eating also affects your internal clock. Food intake boosts metabolic heat production (diet-induced thermogenesis), which in turn affects circadian rhythm. Eating on local time — even if it feels off — helps signal to your body that it has officially arrived.
So yes: take the hot shower in Florence. Sleep in a 64°F room with blackout curtains. Eat breakfast when the city does. Thermoregulate like a monk. Realign like a mammal.
Caffeine is a powerful tool — and like most powerful tools, it can either build structure or cause chaos depending on how it's used. When dealing with jet lag, timing caffeine intake isn't about comfort, it's about hormonal synchronization.
Your body's cortisol rhythm — the natural daily rise and fall of your primary stress hormone — is designed to help you wake up, become alert, and function through the day. Under normal circumstances, cortisol spikes within 30–45 minutes of waking (known as the cortisol awakening response), then gradually declines throughout the day.
During jet lag, this rhythm is misaligned. You might feel foggy in the morning and wired at night — not because caffeine failed, but because cortisol hasn't landed in the right time zone yet.
Here's the strategy:
Don't drink caffeine immediately upon waking.
Wait at least 60–90 minutes after waking in your destination time zone. This allows your natural cortisol surge to peak first.
Once cortisol starts tapering, your first coffee supports the decline rather than competing with it.
Drinking caffeine too early — especially when cortisol is already high — increases the risk of anxiety, jitteriness, and energy crashes later in the day. It also dulls caffeine's long-term effectiveness. Studies show that habitual early caffeine use may lead to tolerance, flattening your natural alertness curve.
And in the afternoon? Avoid it. Research from the Journal of Clinical Sleep Medicine (2013) showed that caffeine consumed even six hours before bedtime significantly reduces total sleep time and sleep quality. So if you're trying to align with local time, that innocent 4PM flat white could sabotage your 10PM lights-out.
Instead, use non-caffeinated alertness cues in the afternoon: movement, sunlight, hydration, even a cold face rinse. If you need something warm and ritualistic, herbal teas or adaptogenic blends can substitute the psychological signal of a coffee break without interfering with your circadian recalibration.
Jet lag recovery is a hormonal choreography. Let cortisol lead. Let caffeine follow. And let sleep reclaim its place at the center of your recalibration.
Jet lag isn't just chemical — it's existential. Beyond melatonin and body temp lies a more elusive disruption: the sense that your identity hasn't caught up with your location.
This dislocation is more than fatigue. It's disorientation. It's the moment you step out of a taxi in Kyoto or Cape Town or São Paulo and feel like your consciousness is still boarding in Heathrow. There is a wordless in-betweenness — not quite here, not quite there.
The remedy? Ritual. Not productivity. Not distraction. Just a few reliable cues that tell your nervous system: you've landed.
Simple, physical rituals work best:
A morning walk, preferably in natural light.
A familiar grooming ritual — shaving, skincare, hair combed the same way.
A local meal eaten slowly and mindfully, at the right local time.
Writing a journal entry that includes the date, time, place, and what the air smells like.
These acts are not performances — they are orientation anchors. Your brain relies on multi-sensory cues to establish context. When you provide structure, you give your cognitive map a foothold.
In psychology, this is known as temporal self-continuity — the sense that you are the same person over time, even in unfamiliar surroundings. Jet lag scrambles that continuity. Rituals stitch it back together.
You don't have to optimize every moment. You don't have to squeeze joy from the schedule. You just have to let your body and mind remember that they're on Earth, in one place, at one time. That's enough.
If you resist the dislocation, it stretches longer. If you meet it — gently, rhythmically — it passes with a kind of grace. Not without discomfort, but without disarray.
So: wash your face. Eat the soup. Step outside. Breathe where you are.
Jet lag doesn't just exhaust you — it fractures you. You leave one version of yourself in a past city, speaking in a different cadence, tethered to another sun. And then, within hours, you are dropped into a new timezone with no emotional preparation. Your biology lags behind your passport.
It's a strange and quiet crisis. You eat dinner when your stomach wants breakfast. You walk under unfamiliar stars, answer emails before dawn, and question whether you're really there — or just borrowing someone else's timeline.
Jet lag is not just an inconvenience of time zones — it's a soft betrayal of continuity. A pause in your internal narrative. For a moment, you don't quite belong to your body, your habits, or even your name.
But that fracture is also an opportunity. Because in the space between identities — the one you left and the one you're stepping into — you have a rare chance to reset. To become local again, not just externally, but internally. To choose a new rhythm, to align deliberately, to arrive not just by plane, but in mind.
The most seasoned travelers learn to savor this in-between state. They don't resist it. They prepare for it. They set small rituals like scaffolding and let the rest fall into place.
So: take the walk. Watch the sky. Open your windows. Breathe into the clock.
You were someone somewhere else. Now you're here. Let yourself arrive.
(Just don't have the wine after 9PM. You'll end up like the squirrel.)
How intermittent fasting can slow aging and boost longevity
What he actually kept after the cameras stopped.
Ancient practices from remote cultures that promote health and vitality
A coastal fitness routine that combines strength and serenity