7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them)

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Airplane Cabin Pressure at 35,000 Feet Equals Sleep at 6,000 Feet Mountain Height

When cruising at 35,000 feet, the air within the airplane cabin is artificially pressurized to levels comparable to being at an altitude of 6,000 to 8,000 feet above sea level. While this might sound harmless, it can cause discomfort for some travelers as it essentially mimics the effects of being at a high elevation. This simulated altitude can trigger feelings of discomfort in some people, especially as lower oxygen levels (hypoxemia) become noticeable at around 7,000 feet. Some newer aircraft, such as the Boeing 787 Dreamliner, are designed to improve comfort by maintaining cabin pressure at a lower equivalent altitude, ideally around 6,000 feet. This aims to reduce these uncomfortable effects and create a more pleasant environment for passengers.

Although aircraft manufacturers constantly improve cabin pressure regulation, the truth is that flying at these high altitudes is never fully comparable to being at sea level. There will always be a noticeable pressure difference and associated potential for discomfort. Understanding this can help travelers prepare themselves for the experience and potentially find ways to alleviate any discomfort associated with the altered cabin conditions during long-haul journeys, ensuring a more pleasant and restful trip.

Imagine the air you breathe at 35,000 feet. It's not the same as what you're used to at ground level. Aircraft cabins are pressurized, but the pressure inside is similar to being at an altitude of 6,000 to 8,000 feet, a considerable height. This artificially reduced air pressure means there's less oxygen available.

While most of us wouldn't notice this difference at a lower altitude, at the altitudes airplanes fly, the air thins out dramatically. As a result, the amount of oxygen our bodies receive decreases, a phenomenon called hypoxia. Though slight, this reduction can impact your well-being, particularly during extended flight times. Studies have suggested that hypoxia can lead to feelings of fatigue, lightheadedness, and potentially even headaches. It certainly does not support a great night's sleep.

It's fascinating how aircraft design factors into this. Newer aircraft models like the Boeing 787 Dreamliner try to maintain a lower cabin pressure equivalent, closer to 6,000 feet. Older models, in comparison, might retain cabin pressures closer to 8,000 feet, potentially making hypoxia and its associated side effects more pronounced.

Airplanes are marvels of engineering, pressurizing the cabin to maintain a safe environment. The pressure control systems carefully adjust cabin pressure during the climb and descent, minimizing the effects of rapid pressure changes. Yet, the unavoidable decrease in oxygen, although kept within safety limits, needs to be considered for its effects on passenger comfort, and, in this context, it also has a link to sleep quality.

What else is in this post?

1. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Airplane Cabin Pressure at 35,000 Feet Equals Sleep at 6,000 Feet Mountain Height
2. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Aircraft Engine Noise at 85 Decibels Matches Downtown City Traffic Volume
3. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - 31 Inch Seat Pitch Forces 20 Degree Recline Instead of Sleep Supporting 45 Degrees
4. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Blue Light From Entertainment Systems Reduces Melatonin Production by 50 Percent
5. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Economy Class Air Temperature Fluctuates Between 19-23°C Disrupting Core Sleep Temperature
6. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Meal Service Times Create 3-4 Hour Light Exposure During Critical Sleep Windows
7. 7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Cross Row Foot Traffic Causes 12-15 Sleep Interruptions During Long Haul Flights

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Aircraft Engine Noise at 85 Decibels Matches Downtown City Traffic Volume

The roar of aircraft engines can be a major nuisance, especially for economy class passengers. During crucial flight phases like takeoff and landing, the noise levels can spike to a remarkable 85 decibels—a level comparable to the din of downtown traffic. This high volume not only makes it hard to have a conversation or even hear the in-flight entertainment system, but also contributes to sleep disruption. This is another challenge for those already experiencing discomfort in a cramped economy seat and makes the search for a relaxing flight experience all the more difficult.

While newer aircraft designs and noise reduction technologies have reduced noise levels over the years, the constant hum and occasional loud bursts still represent a significant barrier to restful sleep at 30,000 feet. For some travelers, it might be worth thinking about noise-canceling headphones or earplugs for a more relaxing flight experience. It's important to acknowledge this factor when planning a trip and to explore ways of mitigating its impact on a good night's sleep on board.

Aircraft engines, especially during takeoff and landing, can generate a significant amount of noise, often reaching 85 to 100 decibels. Modern aircraft like the Boeing 737, demonstrate how engine noise varies across flight phases, with higher levels during takeoff and landing compared to cruising.

Interestingly, the 85 decibel mark for an aircraft engine at cruising altitude is roughly equivalent to the noise levels of a busy city street or downtown traffic. This begs the question: if we find the hum of traffic in a city disruptive to sleep, does the consistent, albeit often muffled, hum of an airplane engine play a similar role?

Regulations, like those set by the Federal Aviation Administration (FAA), are in place to keep aircraft noise in check. The FAA utilizes standards for noise certification of civil aircraft to try and limit this kind of sound pollution. This has led to progress, with significant reductions in community noise exposure over the years, achieved through technological advancements and noise reduction initiatives.

Measuring aircraft noise, like any other environmental sound, often involves calculating the average sound level. Experts use a metric called LAeq, which analyzes the average sound over a defined time, such as a 16-hour day. This helps to understand the general noise levels a community or individuals might experience.

The noise produced by aircraft stems from multiple sources – engines and the movement of air around the fuselage and wings, creating various frequencies and tones. Sensors and traffic statistics are used to capture flight noise in real time and to help assess the noise impact of air traffic.

With the introduction of newer generations of aircraft, noise reduction has become a major design consideration. The goal has been to significantly reduce noise, particularly aiming for noticeable reductions compared to older aircraft like the Boeing 737. For example, the N1 noise goal seeks a 32-decibel decrease in noise from a modern aircraft compared to a Boeing 737, and N2 aims for a 42-decibel reduction when compared to a Boeing 777.

Continuous monitoring and research are pivotal for evaluating the effectiveness of noise mitigation strategies. The FAA, collaborating with the international aviation community, constantly analyzes if noise standards need adjustments as technologies continue to evolve. It's a crucial aspect to maintain a balance between innovation in air travel and preserving quality of life around airports.


While it's fascinating that we've seen such dramatic improvements in noise reduction, it also raises questions. Even with reduced noise levels, the question remains as to how significantly the continuous, relatively high-frequency hum of a modern airliner at cruising altitude impacts sleep and fatigue during long-haul flights. Further research into this area could help us better understand how this unavoidable element of air travel impacts passenger well-being.

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - 31 Inch Seat Pitch Forces 20 Degree Recline Instead of Sleep Supporting 45 Degrees

The typical 31-inch seat pitch found in economy class often leads to a limited recline of just 20 degrees. This is far from the 45-degree angle that many find ideal for comfortable sleep. The restricted recline, coupled with the limited space, significantly reduces the ability to get a decent night's rest on longer flights. Airlines might argue that slimmer seats increase the feeling of legroom, but often this comes at the cost of even less comfort, especially when combined with the restricted recline. Ultimately, this struggle to recline comfortably is a constant source of frustration for travelers seeking quality rest on flights. The pursuit of greater efficiency and maximizing profits sometimes seems to overshadow the importance of passenger comfort, especially when it comes to achieving a relaxing and restful sleep in economy class. The ongoing tension between airline profitability and passenger comfort persists and poses a substantial challenge for those looking for sleep-conducive economy class travel.

The standard 31-inch seat pitch found in many economy cabins presents a challenge for comfort and sleep. This limited space directly impacts the maximum recline angle, restricting it to roughly 20 degrees. While this might seem like a minor detail, the difference between a 20-degree recline and the more comfortable 45-degree recline often seen in business or premium economy is significant.

The human body naturally finds a more relaxed position in a 45-degree reclined posture. This angle supports better spine alignment, which can contribute to a deeper, more restorative sleep. The 20-degree recline, on the other hand, often leaves passengers feeling cramped and less able to settle into a truly restful position.

This reduced recline angle can have consequences beyond just comfort. The ability to breathe deeply and fully, often referred to as diaphragmatic breathing, plays a crucial role in achieving deeper sleep stages. A 20-degree recline can interfere with natural breathing patterns, potentially leading to more shallow and disruptive sleep.

Interestingly, some airlines are starting to explore seat designs that allow for a greater range of adjustability, offering passengers more choices in how they position themselves. These efforts recognize the varied needs and body types of passengers. While a fully customizable seat in economy is probably not on the horizon soon, it demonstrates that understanding the challenges of limited space and recline angle in economy seating is receiving attention.

Another critical consideration is the correlation between limited recline angles and restlessness. Feeling cramped can be psychologically stressful, leading passengers to frequently change positions during the flight, which impacts the quality of sleep. This perpetual movement not only makes achieving deeper sleep phases more difficult but also disrupts others around the passenger.

The effects don't end there; cramped positioning during flights also contributes to physical discomfort, particularly in the musculoskeletal system. Extended periods of limited movement and poor posture can increase muscle strain, pain, and stiffness. This adds to overall discomfort and makes achieving a truly restful sleep even more challenging.

This whole topic highlights how much the interior of aircraft could be improved to accommodate different passenger needs and promote better sleep quality. The current design trends for more modular and adaptable aircraft interiors could also pave the way for better economy seating layouts that focus on optimized seat pitch and recline angles.


Moreover, the effect of sleep disruption from uncomfortable seats on jet lag adds another layer of complexity. Research shows that insufficient or poor-quality sleep, often made worse by limited seat recline and uncomfortable seating, can exacerbate the effects of crossing time zones. The result is an increased recovery period for passengers and potentially a less enjoyable experience upon arrival at the destination.

Interestingly, research also demonstrates that passenger perception of space within a seat plays a considerable role in comfort levels. While objective measurements like seat pitch and width are vital, how a passenger feels within the confines of the seat is also influential. A seat with a more steeply reclined position can create a sense of enclosure, potentially leading to feelings of claustrophobia, regardless of actual dimensions. This shows how design and psychological factors can influence passenger comfort in economy class.

Finally, some modern innovations in airline design such as "twin" or "pod" seat configurations might help address the problems of poor recline and inadequate pitch. This idea of providing more personal space and improving the experience for passengers in economy class is something to look out for in the future of airline interiors. These developments suggest a growing awareness of the impact that proper seat configuration and design has on the well-being of passengers.

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Blue Light From Entertainment Systems Reduces Melatonin Production by 50 Percent

The bright screens found on many aircraft entertainment systems emit a significant amount of blue light. This blue light, particularly wavelengths between 460 and 500 nanometers, can disrupt the body's natural sleep-wake cycle by reducing melatonin production by up to 50%. Melatonin is a hormone essential for regulating sleep, and its decline can lead to difficulties falling asleep and maintaining restful sleep during a flight.

This effect can have a noticeable impact on how passengers feel after a long flight. The disruption to natural sleep patterns caused by blue light can leave travelers feeling fatigued and less able to adjust to a new time zone. This is especially relevant during long-haul flights where the effects of disrupted sleep patterns can linger well after the flight ends. While some airlines have started using technology to minimize the blue light emitted from screens, many have not adopted these technologies yet, suggesting a conflict between passenger comfort and operational costs.

Understanding this connection between blue light, melatonin, and sleep quality is crucial for travelers who prioritize restful sleep during air travel. While the convenience of in-flight entertainment systems is undeniable, being aware of the potential for blue light-induced sleep disruption can help passengers make informed choices about their screen time during flights. Ultimately, for travelers seeking the most restorative travel experience, taking measures to minimize exposure to blue light from entertainment systems, perhaps by using blue-light blocking glasses or simply limiting screen time, can contribute to a more refreshing experience upon arrival at their destination.

The entertainment systems found on many aircraft, particularly those offering in-flight entertainment, emit a significant amount of blue light. Research suggests that this blue light can suppress the production of melatonin, a hormone crucial for regulating our sleep-wake cycle. Studies have shown that exposure to this blue light can reduce melatonin production by up to 50%.

This reduction in melatonin can disrupt the body's natural circadian rhythm, leading to poorer sleep quality. The disruption becomes particularly relevant when considering that our pineal gland naturally ramps up melatonin production during the evening hours as light levels decline. This increase in melatonin is crucial for signaling the body to prepare for sleep.

It's interesting to note that the specific wavelengths of blue light that cause this effect primarily fall within the 460-500 nanometer range. Interestingly, blue light with wavelengths between 380-450 nm appears to have less of an impact on melatonin production. This specific spectral sensitivity reveals a fascinating area of ongoing research.

The impact of light on melatonin production is significant. In a healthy individual, peak melatonin levels at night can be nearly ten times higher than during the day. Thus, the suppression of melatonin production, even if by a seemingly modest 50%, can substantially impact sleep quality and overall sleep health.

The challenge for air travelers is that they are often exposed to this blue light at times that conflict with their body's natural sleep-wake cycle. For instance, many travelers enjoy watching a movie on a screen during a night flight, at a time when their body would naturally be experiencing the highest melatonin levels. This clash between natural biological rhythms and the exposure to artificial blue light could be a major contributor to sleep issues in air travel.

Several studies have indicated that blue light blocking glasses may help mitigate some of these adverse effects on sleep. This potential benefit stems from blocking or reducing the transmission of the problematic blue light wavelengths. However, further research is still required to fully explore the practical effects of these glasses in a range of scenarios and travel settings.


This effect of blue light on melatonin levels brings into sharp focus the importance of light hygiene practices for travelers. Whether it's adjusting in-flight entertainment screen brightness, utilizing blue light filters on devices, or even considering blue-light blocking glasses, paying attention to light exposure can be a valuable strategy for improving sleep quality during air travel, especially for those accustomed to a more regular sleep routine. This is important, as disruptions to sleep can negatively affect energy levels and cognitive function in the following days.

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Economy Class Air Temperature Fluctuates Between 19-23°C Disrupting Core Sleep Temperature

The air temperature in economy class cabins often fluctuates within a narrow range, typically between 19 and 23 degrees Celsius. While airlines aim to mimic the comfortable temperature of a home's air conditioning, these minor fluctuations can disrupt a passenger's natural core body temperature, making it difficult to achieve restful sleep. This temperature regulation often relies on bleed air from the aircraft's Auxiliary Power Unit (APU), which can lead to inconsistent temperatures throughout the cabin.

The preference for a lower temperature range in economy class might stem from the larger number of passengers compared to other cabin classes. This can lead to an environment where maintaining a truly comfortable temperature for everyone is challenging. For those seeking a restful sleep during a long-haul flight, this constant temperature fluctuation can be a major obstacle.

Optimizing the passenger experience, especially for long-haul flights, is a key goal for most airlines. Yet, temperature management in economy cabins often receives less attention compared to other aspects of the travel experience. Implementing systems to ensure a more consistent cabin temperature could greatly improve passenger comfort and sleep quality during flights, a factor that should be prioritized in future cabin design.

Economy class cabins often experience temperature fluctuations between 19 and 23 degrees Celsius. This variability can disrupt the body's natural tendency to lower its core temperature during sleep. Our bodies are finely tuned to initiate sleep in cooler environments, so these fluctuating temperatures can hinder the process.

The use of bleed air from an aircraft's Auxiliary Power Unit (APU) for cabin climate control likely contributes to these fluctuations. Airlines usually aim for temperatures that resemble average home air conditioning, often prioritizing lower temperatures, particularly during peak seasons like summer.

It is important to understand that individual responses to temperature can vary considerably. People's age, metabolic rates, and hydration levels all influence how they feel about the cabin's thermal environment.

Research suggests that a steady 19-21 degrees Celsius is typically most comfortable for the majority of people. However, the range seen in airliners suggests a possible gap between ideal comfort and the cabin's actual environment. This disconnect could be part of the explanation for inconsistent sleep quality among economy class passengers.

Additionally, aircraft insulation properties, combined with the need to maintain cabin pressure, can lead to uneven airflow and temperature distribution. Drafts and cold spots are frequent complaints, highlighting the potential for temperature control challenges in pressurized cabins.

The consequences of disrupted sleep in air travel can be considerable. Sleep specialists point out that insufficient sleep can diminish cognitive function and increase irritability. Temperature variations might be a contributing factor in the higher incidence of passenger fatigue and reduced productivity after long-haul flights.

For longer flights, the challenge is compounded. The constant temperature shifts disrupt the body's natural melatonin production, a key hormone for regulating sleep and sleep-wake cycles. This can make adapting to new time zones upon arrival much harder.

Passengers can mitigate these temperature issues with sensible clothing choices. Layered garments and a light shawl or blanket can help individuals personalize their thermal environment within the limitations of the airplane's system.

Maintaining adequate hydration is also important. Dehydration makes it more difficult for the body to regulate its temperature efficiently, thus impacting sleep quality. The low humidity typical of airplane cabins further compounds this issue.

The differences in temperature control between airlines can also influence the passenger experience. Careful travelers might wish to research the temperature policies of different carriers as a factor in their booking decisions. There are variations in temperature management, and this could make a difference in overall sleep quality during the journey.

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Meal Service Times Create 3-4 Hour Light Exposure During Critical Sleep Windows

Meal service times during flights often extend over a period of 3 to 4 hours, exposing passengers to light during crucial sleep periods. This extended light exposure can disrupt the body's natural sleep-wake cycle, also known as the circadian rhythm. Research suggests that altering the time of meals can change when we feel sleepy and wakeful. Our internal body clock is highly sensitive to light, influencing our sleep patterns. While airlines work hard to keep flights on schedule, meal times seem to be chosen with more consideration for operations than for passengers' sleep comfort. Since bright light suppresses melatonin, a hormone necessary for sleep, extended exposure during the night can make it more difficult to sleep. It's a pity that the need for on-time services seems to be more prioritized than the need for good sleep. If you're a traveler who values rest and well-being, it's essential to understand how flight meal service timing and bright lights can negatively impact your sleep. Perhaps it's time to think about how airlines can better manage meal services and cabin lighting to promote a better travel experience for those seeking restful flights.

The timing of meal services on flights, particularly during overnight flights, presents a curious challenge for passenger sleep. Research indicates that even the relatively brief period of light exposure during these services can significantly disrupt the body's natural sleep-wake cycle.

Our internal biological clock, also known as the circadian rhythm, is finely tuned to the natural light and dark phases of our environment. It's incredibly sensitive to light exposure, particularly in the evening hours. Meal services, with their associated lighting, can disrupt this natural pattern, particularly on long-haul night flights. When the body is preparing for sleep, sudden increases in light exposure can delay the release of melatonin, a hormone that promotes sleepiness.

Adding to the complexity is the natural post-meal dip in alertness we experience after eating, also known as postprandial somnolence. When this occurs alongside a meal service with bright cabin lights, it creates a sort of tug-of-war between the body's inclination to sleep and the effect of the increased light, potentially making falling asleep more difficult.

Moreover, bright light exposure at night can impact the overall structure of our sleep, reducing the time spent in the deeper, more restorative sleep stages. It's as if the light exposure shifts the gears of our natural sleep cycle. Some airlines even employ flashing lights to draw attention during meal services, causing sudden, unavoidable bursts of light that further fragment sleep.

Intriguingly, recent studies on flights from Australia, where "dark cabin" policies were implemented after dinner service, showed marked improvements in passenger sleep and satisfaction. This suggests a tangible link between reduced lighting and improved sleep quality. It's tempting to speculate whether this practice could benefit other regions as well.

Given that cultural dietary customs influence meal service timing on international flights, the problem can become more pronounced when crossing time zones. While a traveler might be used to dining at a certain time, they might find themselves subjected to a meal schedule entirely determined by the airline, creating a jarring mismatch between their natural sleep cycle and the external cues they are encountering.

The situation reveals an interesting opportunity for innovation. Some airlines are experimenting with designated "quiet zones" for meal services, with a focus on minimizing both light and noise. This demonstrates an increasing understanding of how a passenger's environment can contribute to or detract from their well-being during flight.

Based on what we know, it seems reasonable to recommend that airlines meticulously plan meal service timings to better align with passenger sleep preferences. De-emphasizing or minimizing bright lights during those times deemed crucial for sleep may contribute to significantly better passenger experiences. For those on long-haul flights, especially across different time zones, it could be crucial to consider these issues and maybe even make a conscious choice to limit their exposure to light during night-time hours in flight.

7 Proven Sleep-Disrupting Factors in Economy Class Flying (And What Science Says About Them) - Cross Row Foot Traffic Causes 12-15 Sleep Interruptions During Long Haul Flights

The constant flow of passengers through the aisles in economy class during long-haul flights can disrupt sleep significantly, leading to 12 to 15 interruptions during a single flight. This constant movement, combined with the inherent discomfort of limited space and cabin noise, makes it exceedingly difficult to get a good night's sleep. It's not just about a few brief awakenings, but a continuous stream of interruptions that chips away at the potential for restful sleep. This constant disruption, alongside other factors like altitude and cramped seating, can contribute to fatigue and a decline in mental sharpness, especially after long flights. While airlines prioritize operational efficiency and high passenger numbers, there's a clear need for better approaches to managing foot traffic in order to make the overall travel experience more enjoyable. Passengers should be aware of this persistent problem and be ready to adapt and perhaps find their own ways to mitigate the impacts of this sleep-interrupting aspect of flying.



The constant flow of passengers through the aisles of economy class on long-haul flights can be a major disruptor to sleep. Research suggests that passengers situated near the aisles experience a significant number of sleep interruptions, often 12 to 15 times during a single long journey. It seems that this constant flow of individuals going to or coming from the lavatory can fragment the natural sleep cycle and affect the quality of rest passengers achieve.

Interestingly, the mere anticipation of this traffic can also have a psychological impact. Passengers might find it difficult to relax and settle into a comfortable sleep posture, if they constantly worry about being disturbed by the nearby movement. Even slight disturbances, like someone carefully stepping over your feet, can prevent the brain from entering the deeper sleep phases needed for optimal rest. This means that you might simply not get into that rejuvenating deep sleep phase.

It's not just the physical disruption that's at play. The constant interruptions can also impact the body's natural sleep-wake cycle. Melatonin, a hormone that promotes sleep, is influenced by these disruptions, affecting the brain's ability to fully switch to sleep mode. This constant switching back and forth between sleep and being partially awake extends the time it takes to return to sleep after each interruption, meaning you might end up in a very fragmented and shallow sleep mode, with impacts on both physical and mental restoration.

These constant interruptions might explain why many travelers feel excessively tired and mentally sluggish after a long flight. The lack of restful sleep can lead to increased fatigue and cognitive impairment. It's interesting to note that there are often two to four people walking through the aisle per hour in a busy economy class cabin, highlighting the relentlessness of these disruptions throughout the flight.

The cognitive effort needed to process these disturbances, and react to them by consciously changing sleep posture, also adds an extra mental load. Your brain isn't just trying to sleep but also monitoring the environment and getting ready to react to potential disturbances. This constant low-level vigilance can make it more challenging for your mind to settle into the necessary peaceful state for deep sleep.

The situation differs somewhat depending on the airline and aircraft design. Some airlines, understanding the problem of foot traffic, have introduced "quiet zones" or adjusted cabin layout to minimize disturbances in specific sections of the economy class. However, such innovations are not widespread, leaving many travelers with little to no control over the issue.

The growth of low-cost airlines and the increase in travelers has heightened this challenge. Many budget airlines are motivated by filling as many seats as possible to optimize profits. This, in turn, can lead to more congestion in the aisles and more disruption to sleep. The resulting high rates of foot traffic create a tension between maximizing seat availability and maintaining passenger comfort. It's an area that perhaps deserves more attention, especially from a perspective of passenger well-being.

It seems clear that this aspect of the airline passenger experience is an area that could be better understood and addressed. How passengers traverse and interact with cabin space is as critical as the design and dimensions of the seats themselves. There is still much to be learned about how foot traffic and cabin design together impact the overall passenger experience, especially in terms of quality of rest during long journeys.