If you find yourself on a British Airways flight and your airline-supplied blanket turns red, your flight attendant will know you're tense.

That's because you've got a color-changing "happiness blanket."

Last week, British Airways began testing custom-made sleep blankets that feature neurosensors and fiber optics woven into the material.

The sensors measure the wearer's brainwaves, according to a company statement. If that person is tense, the blanket will turn red. Blue indicates the traveler is relaxed. It's similar to a mood ring, except this has science backing it up.

The 'happiness blanket' uses fiberoptic neuro-sensors to measure a person's brainwaves. It changes between red and blue, depending on how relaxed or tense the wearer is. Courtesy British Airways

The airline hopes that monitoring a person's sleep and relaxation patterns will help to change and improve the in-flight experience, providing input about the type and timing of meals and in-flight entertainment.

"Using technology like the 'happiness blanket' is another way for us to investigate how our customers' relaxation and sleep is affected by everything on board, from the amount of light in the cabin, when they eat and their position in the seat," British Airways said in a news release.

This techno-accessory took its maiden voyage on a flight from London to New York City, with volunteers being the first to experience the blankets and have their reactions tracked to identify when and how passengers are most comfortable.

That doesn't mean your flight attendant will offer you a drink if your blanket turns red. While the experiment continues, the blankets will be used only for data collection and not as a way to identify passengers in need of immediate assistance.

But rest assured that someone is taking notes about what you're doing, trying to figure out why you're tense and how British Airways can better help you to relax.