British Airways recently filed a patent on an ingestible sensor that will transmit how you are feeling to the cabin crew. Passengers just need to swallow the digital pill which is about the size of an almond and packaged in silicon.  Once inside the body the digital pill will transmit information to flight attendants e.g. provide water when the passenger is dehydrated, offer a blanket when the passenger is cold or do not disturb or wake up the passenger if they are asleep.  After a day or two the digital pill will pass naturally through the passenger’s digestive system.