Your watch knows you slept five hours. It does not know you crossed six time zones, reported at 02:30, slept in a crew bunk, or have another sector to operate tonight.
That is the problem with wearables for airline crew.
Devices such as smartwatches, fitness bands and rings can collect an extraordinary amount of data. Sleep duration. Resting heart rate. Heart-rate variability. Recovery scores. Activity. Some will even tell you how “ready” you are for the day.
For people working normal schedules, this information can already be difficult to interpret.
For pilots and cabin crew, it becomes even more complicated.
Our sleep moves around the clock. We may sleep during the day, take strategic naps, cross multiple time zones and operate through our biological night. A wearable can measure some of what is happening, but it does not understand the operational context.
That does not make wearables useless.
Used properly, they can be extremely useful.
The key is to track trends, not chase numbers.
- Sleep duration is probably the most useful place to start
Crew often focus on the device’s sleep score.
I would look one level deeper.
How much did you actually sleep?
A wearable can help reveal patterns that are surprisingly easy to miss when your roster changes constantly.
You might discover that:
early reports repeatedly cut your sleep short
eastbound trips affect you differently from westbound trips
you consistently sleep less on the first layover night
a planned nap significantly increases your total sleep across 24 hours
These patterns matter more than whether your watch gave last night’s sleep an 82 or an 87.
Wearables are reasonably useful for following sleep over time, but they are not sleep laboratories. A 2025 meta-analysis involving 24 studies found significant differences between consumer wrist-worn devices and polysomnography, the clinical gold standard, for several sleep measures. The authors nevertheless concluded that wearables can still be useful for tracking general sleep patterns.
For crew, that is exactly where their value lies.
- Do not obsess over sleep stages
Your watch may confidently tell you:
1h 18m deep sleep
1h 42m REM
3h 27m light sleep
Those numbers look very precise.
They are not necessarily that precise.
Wearables estimate sleep stages using combinations of movement, heart rate and other sensor data. They are not directly measuring brain activity in the same way as clinical polysomnography.
Recent validation studies continue to find considerable variability between devices, particularly when identifying wake periods and individual sleep stages.
So if your watch says you only got 47 minutes of deep sleep, there is usually little value in worrying about that number in isolation.
For crew, I would prioritize:
total sleep → sleep timing → sleep regularity → trends
before worrying about exactly how many minutes the algorithm labelled as REM or deep sleep.
- Resting heart rate can provide useful context
Resting heart rate becomes more useful when you know your own baseline.
Suppose your normal overnight resting heart rate is around 55 bpm.
One morning it is 63.
That does not automatically mean something is wrong. Hard training, alcohol, poor sleep, illness, dehydration, travel stress and many other factors can influence it.
But if your resting heart rate remains elevated across several days while you also feel unusually fatigued, that pattern is worth paying attention to.
Again, the important word is trend.
A single measurement tells you very little.
Your personal baseline tells you much more.
- HRV is useful, but easy to misuse
Heart-rate variability, or HRV, measures variation in the time between heartbeats.
Generally, higher HRV relative to your own baseline can be associated with greater parasympathetic activity and recovery, while reductions can occur with physiological stress.
But HRV is highly individual.
Comparing your HRV with another pilot’s HRV is almost meaningless.
Even comparing today’s value with yesterday’s can be misleading.
The useful question is:
What is happening to my HRV over time compared with my normal range?
This is particularly relevant to crew because long-haul travel can combine several stressors simultaneously:
sleep loss, circadian disruption, training load, dehydration, irregular nutrition and psychological stress.
HRV can provide another piece of that puzzle.
It should not become the puzzle itself.
- Recovery and readiness scores are not fitness-to-fly assessments
This may be the most important distinction for airline crew.
A wearable might tell you:
Recovery: 38%
or:
Readiness: Low
That number is produced by the manufacturer’s algorithm using some combination of sleep, HRV, resting heart rate, activity and previous data.
It is useful information.
It is not an aeromedical assessment.
And the opposite is equally important.
A watch showing a 95% recovery score does not prove that you are fit to operate an aircraft.
Fitness for duty involves far more than what a consumer wearable can measure. Aviation fatigue management considers sleep history, time awake, circadian timing, duty schedules and the crew member’s own assessment, among other factors. FAA fitness-for-duty guidance similarly places responsibility within a broader fatigue-management framework rather than reducing fitness to a biometric score.
Think of recovery scores as information, not clearance.
- Activity data can expose another problem with flying
Flying can involve surprisingly little movement.
Hours seated in the flight deck.
Hours in a crew seat.
Transport to the hotel.
Hotel room.
Transport back to the airport.
A wearable makes inactivity visible.
Step counts are not a perfect measure of fitness, but they can remind you how little you have moved during a long duty day and encourage simple countermeasures when circumstances allow: walking around the terminal, taking a short walk on a layover, using the hotel gym or simply adding movement during the day.
For crew, sometimes the value of a wearable is not sophisticated physiology.
Sometimes it is simply saying:
You have barely moved today.
The metric your wearable cannot measure
There is one piece of data more important than anything appearing on your wrist.
How do you actually feel?
If you are struggling to keep your eyes open, having difficulty concentrating or experiencing significant fatigue, a green recovery score should not convince you otherwise.
Likewise, one bad night and an ugly red score do not necessarily mean something is medically wrong.
Consumer sleep technology has improved substantially, but professional sleep organisations continue to caution against treating it as diagnostic technology. The American Academy of Sleep Medicine notes that consumer sleep devices can provide useful information but should not replace proper clinical assessment.
The JetLagWellness approach
For airline crew, I would use a wearable to follow five things:
Sleep duration
Sleep timing
Resting heart rate trends
HRV trends
Activity
Then add the piece no wearable can provide:
How you feel and how you are functioning.
Do not chase perfect sleep scores.
Do not panic over one bad HRV reading.
And do not allow an algorithm to decide whether you are fatigued.
Use the technology for what it does well:
spotting patterns that are difficult to see when your life runs across rosters, night flights and time zones.
Your wearable should help you understand your body.
It should not replace listening to it.
JetLagWellness
This was published on our substack as well
https://substack.com/@jetlagwellness/note/p-218958483?r=7xzduk