Why caffeine makes some people buzz - and others barely notice

Sleep researchers frequently advise avoiding caffeine at least six hours before bedtime. Dr Lindsay Browning, a scientist and sleep expert, says, "I'll suggest to radical that they mightiness privation to debar caffeine aft astir 2pm if they are going to furniture astur 10pm," she says. "But a broad hard-and-fast regularisation isn't helpful, due to the fact that it doesn't truly let for the intricacies and the individualisation of what's truly going on," she adds. The NHS advises pregnant women to keep caffeine intake below 200mg a day, roughly two mugs of filter coffee, as studies have linked higher consumption to lower birth weight and other complications. For most adults the key is moderation, since sensitivity to caffeine varies widely from person to person. "Caffeine is comparatively safe," says Peter Rogers, emeritus professor of nutrition at the University of Bristol. "If you devour a large woody of it, you just commencement feeling jittery and unpleasant and you commencement realising, 'I request to halt this, there's nary constituent taking immoderate more'." Caffeine overdoses are rare and serious poisonings almost always involve concentrated caffeine products, where several grams can be swallowed in a matter of minutes. For coffee lovers the good news is that, if anything, that regular (if expensive) morning habit is linked to improved health outcomes. While researchers cannot be certain that coffee is the sole reason, decades of studies suggest that people who drink it in moderation tend to have lower risks of several major diseases and may even live somewhat longer than non‑drinkers.