By Markham Heid
March 18, 2014

For some reason, green beer was harder to resist than the normal stuff-and if you had one too many yesterday, there's a reason your head feels like someone thumped it with a kettlebell. The moment you took that first sip, your nervous system released a flood of chemicals into your brain, leading to the emotional and physical repercussions you felt (and are still feeling) hours later. Here's a step-by-step, minute-by-minute tour inside your noggin on those occasions when you party a little too hardy.

00:01:00: Alcohol molecules are so small that they permeate cell walls easily, reaching your brain within one minute of your first swallow, explains Joshua Gowin, Ph.D., a neuroscientist and alcohol researcher at the National Institute of Alcohol Abuse and Alcoholism. And while booze is classified a depressant, you experience just the opposite feeling after your first few sips, Gowin says, because the sudden introduction of alcohol into your noodle triggers the release of norepinephrine, a neurotransmitter that drives good-vibe feelings of elation and excitement.

01:00:00: As your breath alcohol content (BrAC) rises, norepinephrine chemicals arouse your senses. An hour after your first drink, you're more alert and stimulated, and you feel more social. Norepinephrine also appears to up your impulsivity, which may explain the random guys you could feel comfortable cozying up to, Gowin says. [Tweet this fact!]

03:00:00: Hours into the night, your BrAC begins to level off as the pace of your drinking slows. You probably feel sluggish and relaxed, and possibly a little confused or depressed. Since the release of norepinephrine has dropped off, you're no longer feeling the excited high you experienced after your first drinks. The change in mood could have to do with an increase in GABA neurotransmitters, chemicals that blunt your brain's activity and prevent your nerve cells from firing. Probably as a result of these GABA chemicals, there's decreased activity in your brain's prefrontal and temporal regions, which are responsible for memory formation and decision-making, Gowin says. There's also an activity slump in a brain region called your cerebellum, which is responsible for motor functions like walking and talking. (So that's what caused that mystery bruise on your arm!)

05:00:00: You have no problem falling asleep. But the presence of alcohol and the chemical cocktail it mixes in your head disrupts the deep, restorative slumber that you'd experience sober-and that you need to function your best come morning. Your brain is able to descend into stage 1 and stage 2 sleep, but not stages 3 and 4 (also known as the "delta wave" and "REM" stages), which your mind and body require to feel its best. As a result, you feel drowsy and tired the morning after a binge, even if you slept in, Gowin says.

13:00:00: Cue the thirsty feeling. Alcohol suppresses a hormone called vasopressin, which tells your body to hold onto its water stores. As a result, you pee more and wind up dehydrated, Gowin explains, and this leaves you queasy and makes your head ache. There's also evidence that the byproducts created as your body processes alcohol can lead to an increase in inflammation-causing agents that make you feel generally "icky" and brain dead. Your B vitamin levels could also be down, hampering your body's ability to make proteins and clear waste, Gowin adds.

14:00:00 How long your hangover lasts depends on about a dozen factors, from what exactly you draink to your size and the foods you consumed before or during your binge. But a breakfast of berries and eggs can help replenish B vitamins, possibly easing your hangover symptoms, Gowin says. Drinking water or electrolyte-rich beverages like Gatorade can help with dehydration too. And a note for next time: Taking an aspirin or Advil before you go to bed can help block the formation of the inflammation-causing agents, Gowin adds.