What practices do airlines apply to avoid jet lag?

Cabin service really doesn't have that big of an impact, since its more towards disturbing passengers at certain phases of flight; and a lot of what can be done as far as the crew is concerned with safety and not necessarily passenger comfort.

For example, at landing and take off (no matter what the time of day), the blinds have to be raised and if at night, the lights are off to avoid glare and increase visibility.

During turbulence, the cabin lights come on as well (during night flights); and if its severe enough, in-cabin service can also be completely stopped.

Keep in mind the primary concern of the aircrew is the safety of the flight; and sometimes this comes at the expense of amenities and perhaps comfort.

However one area that the airlines definitely try to market as "jet lag proof" is their aircraft, and this is also a big marketing push for manufacturers when selling their new airframes.

Consider the 787 and the yet to be released 777X, that have (specifically for passenger comfort):

1. Higher cabin ceilings
2. Larger windows
3. Different light temperatures in the cabin (this leads to more disco lights as the crew plays with them, but it is designed to keep the cabin lights either warm or cool depending on the time of day of flight; rather than the fixed lighting of other aircraft that can just be dimmed or brightened)
4. Lower cabin altitude; which increases cabin pressure.
5. Higher humidity

All these contribute to the overall wellness of passengers; and specifically contribute to the reduction of jetlag.

Here is an article on BusinessWeek quoting Boeing on these changes:

For most of us, a long flight is usually followed by some combination of symptoms that include headaches, lack of appetite, lack of energy, nausea, and sleeplessness.

All of these afflictions have been conveniently bundled together with a disruption of one's internal body clock to form something we call jet lag.

But the reality is that jet lag is far more serious.

The very symptoms we attribute to jet lag may actually be attributed to acute mountain sickness, which affects individuals exposed to altitudes above 6,500 feet.

In a study conducted by Oklahoma State University with the help of Boeing, researchers wrote:

"Some passengers on long commercial flights experience discomfort characterized by symptoms similar to those of acute mountain sickness. The symptoms are often attributed to factors such as jet lag, prolonged sitting, dehydration, or contamination of cabin air. However, because barometric pressures in aircraft cabins are similar to those at the terrestrial altitudes at which acute mountain sickness occurs, it is possible that some of the symptoms are related to the decreased partial pressure of oxygen and are manifestations of acute mountain sickness."

The study found that passengers who go from sea level up to 8,000 feet of altitude saw the oxygen content in their blood fall 4%. Although this didn't trigger full on acute mountain sickness, it did bring on what the study called "increased prevalence of discomfort after three to nine hours" of exposure.

"The research showed passengers' bodies reacted at 6,000 feet similar to that at sea level," Emery said. "So we decided to pressurize the Dreamliner at 6,000 feet."

At 6,000 feet, the cabin air is more dense and has a greater level of oxygen saturation. As result, the body does not have to work as hard to oxygenate blood and sustain itself.

According to Emery, since there isn't a perfect one-to-one correlation between altitude and jet lag, Boeing has taken additional measures to mitigate the symptoms. These measures include an increase in cabin humidity as well as a new air-filtration system.

I have to say, on my first ever 787 flight it has had an effect on my normal grogginess / sluggishness and especially the reduction of dry eyes that would kill me on most long haul flights.