Flexible Economy is a new enhanced Economy service operating on a single cabin aircraft for customers on our shorthaul network flying to and from London Heathrow.
Although caffeine is generally safe and well tolerated, it can cause side effects when ingested in large doses. Additionally, regular caffeine use can cause dependency, resulting in withdrawal symptoms when caffeine is not consumed. Headaches can be a symptom of either too much caffeine or too little.
Try to stay off caffeine completely for a month to see if you feel less tired without it. You may find that not consuming caffeine gives you headaches. If this happens, cut down more slowly on the amount of caffeine that you drink.