Hi, I am Mara
I spent most of my twenties on rotating late shifts. Warehouse nights first, then a hospital switchboard, then a call center that closed at 2 a.m. and expected me back at noon. Through all of it I slept through alarms. Two alarms. The phone across the room. A friend once rang my landline for ten minutes and I never heard it.
The thing that finally worked was not a louder clock. It was a spreadsheet. One column for the time I had to be up, one for how long I take to fall asleep, and a row for every number of sleep cycles I could fit before then. I started going to bed at the time the row said instead of when the shift happened to end, and within a couple of weeks I was waking up before the alarm. Later I added a column for the hours I had missed that week and one for my last coffee.
That spreadsheet is the pillow math this site is named after. I still keep it, I work days now, and I still count back from the alarm every night out of habit.
This is Waffles
An orange and brown tabby who wakes me at 5:40 every morning whatever the alarm says. She has never once read a study. She is the reason I can be funny about mornings, and the reason my own last cycle ends at 5:40 whether I planned it or not.
How this site works
Every article and every calculator here is mine. When I give you a number I say where it came from: the cycle lengths from Carskadon and Dement, the hours per night from the National Sleep Foundation panel, and so on. When a number is a rule of thumb, I call it a rule of thumb. When I have tried something on myself, I say what happened, including the times it did not work.
The calculators run in your browser and store nothing except whether you prefer a 12-hour or 24-hour clock. There is no account, no newsletter and nothing to buy.
What I am not
I am not a doctor, a nurse or a sleep coach, and nothing here is medical advice. If you lie awake for an hour most nights, wake at 3 a.m. and stay awake for weeks on end, snore hard enough to wake yourself, or feel wrecked after nine hours in bed, that may be insomnia or sleep apnea, and a calculator cannot see either. Please take it to a doctor. I would rather say that plainly than have you rearrange your evenings around a number that was never the problem.
If you want to try the arithmetic tonight, the sleep calculator counts back from your alarm for you. The articles have the longer version, with the studies named.