Young, well educated and constantly drunk

1. Women who can hold their liquor are most at risk for blackouts.

Blackouts don’t happen to people who vomit after a few shots or fall asleep halfway through a bottle of wine. The risk factors for blacking out are drinking lots, drinking fast and skipping meals. Hepola, who is five foot two but could go beer for beer with a six-foot-three guy, checked off all those boxes. Women experience more blackouts than men because their bodies metabolize alcohol differently and hormones affect how quickly they get drunk.

2. Blacking out is not the same as passing out.

When your blood hits a certain alcohol-saturation point — around a 0.20 to 0.30 blood-alcohol level — the hippocampus shuts down; it’s the part of the brain responsible for making long-term memories. But your short-term memory still works and you can continue to function. “You can talk and laugh and charm people at the bar with funny stories of your past,” writes Hepola. “You can sing the shit out of ‘Little Red Corvette’ on a karaoke stage.” But you won’t remember any of it.

3. Your friends will remember what you did.

Hepola was both reliant on her friends to fill in the pieces of a blackout night and frightened of what she was going to hear: “How did we get home last night?” she’d ask. “Do you have any idea what happened to my jeans? Why is there a corn dog in my bed?” Of course, it wasn’t all funny anecdotes. She alienated many friends by saying and doing things she’ll never remember. Others distanced themselves because they couldn’t handle worrying about her. It also made romantic relationships tough. One therapist told her that “men leave women who drink too much.”

4. Eventually, you’ll have the mother of all blackouts.

Hepola first asked herself if she had a drinking problem at age 20. During her 30s, she found herself stuck in a cycle of worry: “Am I an alcoholic? Is alcoholism a disease?” And then she had a particularly harrowing blackout night that scared her straight. While on a writing assignment in Paris, she found herself in a strange hotel room on top of a strange man — with no memory of how she’d got there. “Alcoholism is a self-diagnosis,” she writes. “Science offers no biopsy, no home kit. Doctors and friends can offer opinions, and you can take a hundred online quizzes. But alcoholism is something you know in your gut.”

Blackout: Remembering the Things I Drank to Forget, $29.

Related: Are you drinking too much? 4 quick ways to find out