Of all the signals in an AS record, morning stiffness is the one clinicians ask about most directly, and the one people measure least consistently. "A while" and "ages" are not durations.
Why morning stiffness in particular
Pain and stiffness that are worse in the morning and at night, and that ease with exercise rather than rest, are among the symptoms the NHS lists for AS (NHS), and are part of what a clinician weighs when assessing whether back pain is inflammatory. That is also why the BASDAI dedicates two of its six questions to it — one for how severe the stiffness was, one for how long it lasted — and averages the two so the symptom carries the same weight as fatigue, spinal pain, joint pain and tenderness (NASS, The Bath Indices).
Measuring duration
Duration is the number a clinician can use. Decide on a consistent end point — "when I can bend to put socks on without thinking about it" is a common one — and estimate the time from waking to that point. Bands are fine; precision to the minute is not the goal.
| Band | BASDAI duration (approx.) | Note |
|---|---|---|
| None | 0 | Loosened up on waking or within a few minutes |
| Under 30 minutes | 1–2 | |
| 30–60 minutes | 3–5 | 1 hour is the scale’s midpoint |
| 1–2 hours | 6–9 | |
| 2 hours or more | 10 | The scale caps here; longer is still recorded as 10 |
Measuring severity
Severity is a 0–10 judgement of how stiff you were, not how long. A short but severe stiffness and a long mild one are different experiences, and the two numbers together describe your morning better than either alone. Record them separately, as HAVYT’s check-in does.
When to record it
Later the same morning, once it has resolved — you cannot know the duration before then. A fixed slot (with breakfast, on the commute) keeps it consistent. If you forget until evening, record your best estimate and mark it as one.
Reading the trend
A single morning tells you about that morning. Over weeks, look at the average duration and at the number of mornings above your usual band. A drift upward sustained over several weeks is worth raising at a review; so is a change in the pattern, such as stiffness that used to resolve by nine and now lasts into the afternoon.
It is also worth looking at what sits beside the stiff mornings in your own record — sleep in particular, and activity the day before. An association there is a question for your team, not an answer. See sleep and ankylosing spondylitis.