When a clinician asks how your pain has been, you answer from memory, and memory is a poor witness. In a study of patients who rated their pain as it happened during a colonoscopy or a kidney stone treatment, the total pain they reported afterward tracked the worst moment and the last few minutes, while the length of the procedure barely registered. A week of pain gets the same treatment: one bad evening stands in for all of it. A pain journal keeps the record while it is fresh, so the appointment starts from what happened rather than from what stuck.

What goes in each entry

Each entry is a handful of taps and, at most, two short lines of writing.

• Where. Tap the front or the back of the body chart, up to four places. On the front figure your right side sits on the left, as it would on someone facing you.
• How much. A number from zero, no pain, to ten, the worst you can imagine: the scale clinics commonly use.
• What kind. Aching, sharp, burning or throbbing, one or two of them. The word is worth the tap, because different kinds of pain send a clinician toward different questions.
• When, and after what. The hour, and what came before it: sitting or standing a long time, housework, driving, a poor night's sleep, stress, cold or damp weather, just waking up.
• What eased it. Rest, heat, a cold pack, stretching, a warm shower or nothing yet. If you took medicine, write its name and dose and set the hour you took it.
• A few words. Where you were, or what the pain kept you from doing.

How the day clock reads your entries

Every entry becomes a dot on a twenty-four-hour clock, noon at the top, placed at its hour and further from the center the more it hurt. Behind the dots, a petal for each three-hour stretch shows the average there, and a stretch holding a single entry stays faint.

Once you have six entries over two days or more, with at least two stretches of the day holding two entries each, the page compares them. When one runs two points or more above another, it names both in words: between 6 and 9 pm, say, six out of ten against two and a half in the late morning. Otherwise it tells you the pain holds about level.

It also looks at your higher entries, the ones a point or more above your own average, and checks what you marked before them. When one thing comes before at least half of them, and clearly less often before the lower ones, the page says so: four of your five entries at six or more came after sitting a long time. Change an entry or remove one, and the clock, the reading and the summary all follow.

The summary gathers the rest for your appointment, down to any medicine and the hour you usually took it. When you print, the entry form stays off the paper.

What the evidence says, and what it doesn't

Pain often keeps a daily rhythm. When researchers went back through two drug trials in people with nerve pain from diabetes or after shingles, pain ratings rose from morning to evening, by about a third between 8 am and 8 pm in the newer trial. That is one kind of pain in one pair of trials, and yours may keep different hours, which is why the clock reads your own entries instead of borrowing a schedule from a study.

What a journal cannot do is tell you why. A pattern in your entries is a question worth raising, not a cause and not a diagnosis. Sitting may come before your worst evenings because it matters, or simply because evenings are when you sit. It also helps to log at one or two set times each day, the easier hours included: a journal kept only on the bad days will make every hour look bad.

When to put the journal down

Some pain calls for help now, not a pattern later. Call 911 for chest pain or discomfort that lasts two minutes or more, or for sudden, severe pain anywhere in your body; both are on the warning signs of a medical emergency that MedlinePlus lists. Do the same for sudden weakness, or numbness on one side of the body, which can be signs of a stroke. Pain that is new, or unlike your usual pain, deserves a call to your clinician rather than another week of entries.

Months of pain can wear down your mood as much as your body. If it ever has you thinking about ending your life, call or text 988 in the US, or your local emergency number, today.

When to use it

Start two weeks or so before an appointment, or when a treatment begins or changes. If a poor night's sleep keeps turning up before your higher entries, a Sleep Log can show what your nights actually look like. If the pain lives mostly in your head, the Headache Diary is built around headaches instead. And when the day of the appointment comes, bring the summary along with your list of Questions to Ask Your Doctor.