What I have worked out about sleep so far, with the arithmetic shown and the study named. Newest at the top.
Sleep calculator
Is a sleep calculator accurate? The arithmetic is exact, but it rests on a 90 minute average. Where it holds, where it drifts and how I tune mine to fit me.
Read more: Is a sleep calculator accurate? The math is exact, the 90 minutes is not
Sleep schedule
How I improve sleep hygiene with light, a fixed wake time and a caffeine clock, the studies behind each habit, and the popular tricks that did nothing for me.
Read more: How to improve sleep hygiene, from the shift years when I got it all wrong
Sleep science
The 90 minute sleep cycle is an average. Yours may run 70 to 110 minutes. Here is where the number comes from and what the sleep calculator assumes.
Read more: The 90 minute sleep cycle is an average, and yours may be 70 or 110
Alarm apps
Low tones, bed shakers, missions and placement: what an alarm clock for heavy sleepers needs, the studies behind it, and the products I tried myself.
Read more: An alarm clock for heavy sleepers, from someone who slept through three of them
Alarm apps
Alarmy's missions got me out of bed, but the ads and subscription grated. Here is the Alarmy alternative I use and the plainer alarms worth testing tonight.
Read more: An Alarmy alternative, and what Alarmy still gets right
Sleep schedule
My 30 minute bedtime routine, built backwards from the calculator's bedtime, with the studies behind each step and the parts I tried and dropped.
Read more: A 30 minute bedtime routine, counted back from the time your alarm goes off
Alarm apps
I compared Alarmy, Sleep Cycle, Sleep as Android, Wayk and the stock clock by one test: which alarm clock app actually gets you standing up on a bad morning.
Read more: Which alarm clock app actually gets you out of bed
Caffeine
How long before bed should I stop drinking coffee? What the Drake 2013 study found at six hours, the half-life arithmetic, and how I set my own cut-off.
Read more: How long before bed should I stop drinking coffee? Six hours is the floor, not the answer
Waking up
If you can't wake up in the morning, count the sleep you are short and where your alarm lands before you try new habits. Here is what I checked first.
Read more: Can't wake up in the morning? Check your sleep debt first
Naps
How long should a nap be? About 20 minutes or a full 90, not 30 to 60. The studies behind both lengths, and how I set the alarm so I wake clear.
Read more: How long should a nap be? 20 minutes or 90, and why I stopped taking 45
Waking up
How to become a morning person without lying to yourself: what the chronotype studies say moves, what stays put, and the light and alarm plan I use.
Read more: How to become a morning person, and which parts of you will not budge
Waking up
How to get out of bed in the first 90 seconds after the alarm: light, feet on the floor, one small task, and the research on why lying there makes it worse.
Read more: How to get out of bed in the first 90 seconds, with a cat as the enforcer
Sleep schedule
How to reset sleep schedule drift two ways: 15 minutes earlier a night, or one short night. When each one works, and why a single all-nighter rarely holds.
Read more: How to reset your sleep schedule, 15 minutes a night or one long day
Waking up
How to stop snoozing, from someone who hit it nine times a day: why the habit sticks, one alarm across the room, and a bedtime that lands on light sleep.
Read more: How to stop snoozing when your hand finds the button before you do
Waking up
How to wake up early without forcing it: move your bedtime 15 to 30 minutes at a time over two weeks, with the sleep math and studies I used to do it.
Read more: How to wake up early by moving your bedtime, not your willpower
Alarm apps
A loud alarm worked on me for nine days. Here is what the research says wakes a sleeper: pitch, a sound that changes, and when in the cycle it rings.
Read more: Why a loud alarm stopped waking me, and what wakes a sleeper instead
Alarm apps
A math alarm clock makes you solve a sum before it stops. Here is why that wakes a groggy brain, what the research says, and how hard the problem should be.
Read more: Why a math alarm clock works on a brain that is still half asleep
Sleep schedule
The night shift sleep schedule I pieced together on rotating shifts: a fixed anchor sleep, sunglasses on the drive home, and coffee only early in the shift.
Read more: My night shift sleep schedule, built from years of getting it wrong
Sleep schedule
Sleep debt builds quietly. Here is how I count it, what Van Dongen 2003 and Kitamura 2016 found, and why a weekend lie-in only pays back part of it.
Read more: What sleep debt is, and why one long Saturday never paid mine back
Sleep calculator
Start from your alarm and count back in sleep cycles. Here is the arithmetic I use, the studies the numbers come from, and how much they can be trusted.
Read more: What time should I go to bed?Sleep schedule
What time should I wake up? Add the time it takes to fall asleep, count forward in 90 minute cycles, and set the alarm where a cycle ends, not in the middle.
Read more: What time should I wake up? Count forward from the minute you fall asleep
Waking up
Why do I sleep through my alarm? For me it was sleep debt, deep sleep at the wrong minute, and a ringtone my brain had learned to ignore. Here is the math.
Read more: Why do I sleep through my alarm, and what finally fixed it for me
Waking up
Why do I feel groggy after waking up? Sleep inertia, the studies that measured it, how sleep cycles fit in, and what I changed so my mornings got clearer.
Read more: Why do I feel groggy after waking up? What the fog is and how long it lasts