By Dr Chun Tang — MBChB (Manchester), MRCGP, MBA · Practising NHS & Private GP · Founder, Little Ox

NMN and Travel: Energy on Long Flights, Jet Lag and Why Your Cells Struggle at 35,000 Feet

I travel a fair amount for work — board meetings, conferences, speaking engagements. And in 26 years as a GP, I've had more conversations than I can count about why travel is so exhausting, why jet lag is worse as you get older, and what actually helps beyond melatonin and willpower.

The cellular biology of travel is genuinely interesting, and it connects directly to NAD+ in ways that most people haven't heard about. This post explains what's actually happening in your body on a long flight, why it gets harder with age, and where NMN fits in honestly.

What a Long Flight Actually Does to Your Biology

Commercial aircraft cabins are pressurised to the equivalent of roughly 6,000–8,000 feet altitude — not sea level. At that pressure, blood oxygen saturation drops slightly but measurably. Your body compensates, but the compensation costs energy. Every cell in your body is working slightly harder than it would on the ground just to maintain normal function, and it's doing so while you're typically sitting still, dehydrated and in a recirculated air environment for 8–14 hours.

The dehydration effect is significant and underappreciated. Cabin humidity is typically below 20% — lower than most deserts. At that humidity, you can lose over a litre of fluid on a long-haul flight without feeling obviously thirsty. Dehydration directly impairs mitochondrial efficiency, reduces cellular metabolism production and makes the fatigue you feel on arrival substantially worse than it needs to be.

On top of the physical stress, long-haul travel typically means disrupted sleep — either attempting to sleep in an uncomfortable position at the wrong time for your body, or arriving at a destination where it's daytime when your biology says it's 3am. This is where jet lag's central mechanism kicks in.

Jet Lag Is a Circadian Problem — and NAD+ Regulates Your Circadian Clock

Jet lag is not simply tiredness. It is a genuine physiological desynchronisation between your internal biological clock and the external environment at your destination. Your circadian rhythm — the 24-hour cycle governing sleep, waking, hormone release, digestion, body temperature and cognitive performance — is anchored to your departure time zone. After crossing three or more time zones rapidly, every internal process is running on the wrong schedule.

The most significant symptoms — poor nighttime sleep, daytime sleepiness, reduced cognitive sharpness, irritability, impaired memory and gastrointestinal disturbance — are the direct consequence of that desynchronisation. A 2024 systematic review in Cureus covering studies from 2020–2024 confirmed that circadian misalignment is the primary driver of these symptoms, and that resynchronising the circadian clock is the primary therapeutic target.

Here is where NAD+ becomes directly relevant. NAD+ doesn't just power cellular metabolism — it is a core regulator of the molecular clock itself. The circadian clock genes (CLOCK, BMAL1, and the SIRT1 deacetylase that rhythmically activates them) all depend on NAD+ for their proper function. SIRT1 — one of the sirtuins that NMN activates via NAD+ — directly deacetylates and regulates BMAL1, a master transcription factor in the circadian system. When NAD+ is depleted, SIRT1 activity falls, BMAL1 regulation is impaired, and the circadian clock loses precision.

This matters for jet lag in a specific way: the speed at which your circadian clock can re-entrain to a new time zone depends partly on how well the molecular clock machinery is functioning. Lower NAD+ levels — which are the baseline reality for anyone over 40 — mean a less responsive, less efficient circadian clock. This is a direct biological explanation for why jet lag gets harder to recover from as you age.

The NADH and Cognitive Performance Study

The most directly relevant human evidence comes from a double-blind, placebo-controlled trial that tested stabilised NADH (the reduced form of NAD+) as a countermeasure for jet lag cognitive impairment. Participants flew overnight from West to East Coast USA, crossing three time zones. Those who received NADH performed significantly better on four cognitive measures — including working memory, divided attention and visual perceptual speed — and reported less sleepiness compared with placebo. No adverse effects were observed.

NADH is downstream of NAD+ in the cellular metabolism pathway — NMN raises NAD+ which supports the NAD+/NADH system. The cognitive protection this trial demonstrated is mechanistically consistent with what NMN does at the cellular level. No direct NMN-specific jet lag trials exist yet, but the biological pathway is the same.

The Energy Cost of a Long Flight — Why NMN's Mitochondrial-Related Research Matters

Beyond circadian disruption, long-haul travel imposes a significant cellular metabolism demand. The mild hypoxia of cabin pressure, the immune activation from recirculated air and close proximity to other travellers, the physical stress of immobility followed by sudden movement through airports, and the disrupted sleep all draw on the same mitochondrial energy reserves. PARP enzymes — which are activated by cellular stress and DNA damage — consume NAD+ when they are running, and the accumulated stresses of a long flight activate them.

The traveller who lands from a 12-hour flight and feels genuinely depleted — not just tired, but emptied — is experiencing what mitochondrial energy deficit feels like in practice. NMN supports the cellular metabolism production system that these stresses draw down. Taking NMN as part of your travel routine means going into a long flight with better-supported cellular metabolism reserves, and recovering more efficiently afterwards.

Practical Travel Protocol

Frequent Flyers and Business Travellers

For people who travel regularly — monthly long-haul trips, multiple time zone crossings, early morning and late night connections — the cumulative effect on circadian health is significant. Chronic circadian disruption is associated with metabolic dysregulation, impaired immune function and accelerated biological ageing. Flight crew and frequent business travellers consistently show elevated markers of circadian stress.

For this group, consistent NMN supplementation isn't just about managing individual trips — it is about maintaining the cellular metabolism and circadian regulation infrastructure that chronic travel erodes. At £9.99 a month for NMN Plus, it is one of the lowest-cost interventions available for a very real physiological challenge.

Shop NMN Plus — from £9.99 → Shop Magnesium Glycinate — £9.99 →

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This article is for informational purposes only and does not constitute medical advice. NMN is a food supplement, not a medicine. If you have a health condition or take prescription medication, consult your GP before starting any new supplement.