Guides · Baby monitors · False alarms
Why Angelcare pad alarms when baby is still breathing
What does an Angelcare alarm actually mean?
Angelcare’s AC117 false-alarm article opens with the maker’s own definition: the alarm means the nursery unit has not received a movement signal from the sensor pad for 20 seconds. The pad is watching the surface of the mattress. It is not running a medical breath count. Angelcare’s bedside-crib article says the same thing in one line: the sensor pad is designed to detect the baby’s movement, not their breathing.
So a baby who is clearly breathing can still set the alarm off, if too little of that breathing is reaching the pad — or if you lifted the baby out and left the pad armed. The reverse error is just as important: if something else is shaking the mattress, the pad can stay quiet while you assume it is watching the baby. Which? notes that some parents find pads reassuring and others find false alarms raise anxiety. The Lullaby Trust’s coordinator factsheet says false alarms may heighten anxiety and disturb sleep, and that they happen when a sensor detaches or abdominal movements become too slight to detect.
If the alarm sounds, the Lullaby Trust still wants you to check the baby first: look for chest or tummy movement, feel or hear breath, stimulate by talking or tickling the feet — never shake — and dial 999 on speaker if there is no response. Only then treat the episode as a set-up problem.
Why does the pad miss a baby who is still breathing?
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| What you did or have | What the pad sees | What the maker or charity says to check |
|---|---|---|
| Baby lifted out; pause not used | An empty mattress for 20 seconds | Angelcare’s AC117 manual: the most common false alarm is leaving the nursery unit on after you take the baby out. Use the published pause control, then un-pause before the baby goes back |
| Thick foam, memory foam, or a dual-sided memory-foam mattress | Movement soaked up in the foam, so little reaches the pad | Angelcare: the pad is not for full or partial memory foam, hollow-frame mattresses or water beds. Standard sprung or coir-type mattresses are the ones the help pages say transfer movement |
| Slatted or sprung cot base, no board | Pad tilting between slats as the baby wriggles | Angelcare install pages: a hardboard at least 30 × 30 cm and 6 mm thick, larger than the pad, between the base and the pad — see the hardboard guide |
| Sensitivity too low for this mattress | Edge-of-cot movement never reaches the threshold | Four-corner test (below). Factory preset on many models is level 3; a thicker mattress needs a higher setting in the AC117 manual’s wording |
| Fan, mobile, loud music, someone touching the cot | Extra motion — or, if you then turn sensitivity down, a pad that later misses the baby | Angelcare: the pad cannot tell a fan or a mobile from the baby. Turn those off before you chase the sensitivity dial |
| Sensor pad detached or sitting on a fold | No firm contact with the mattress underside | Lullaby Trust coordinator factsheet: false alarms when the sensor pad becomes detached, or movements are too slight |
How do I run the four-corner test?
This is Angelcare’s published sensitivity check, not a MayTally invention. The baby must be out of the cot. You are asking two questions: does the pad see a light hand in every corner, and does the alarm sound when you step away?
- Put the pad in the centre, printed side up, under the mattress No bedding between pad and mattress. If the base is slatted, add the hardboard the manual names, or sit the pad edges over at least two slats. Step away — Angelcare says the pad can read you if you are touching the frame.
- Switch both units on and wait After about 20 seconds with no one on the mattress, the movement alarm should sound. If it does not, sensitivity is too high for an empty cot (the pad is still ‘seeing’ the room). Turn it down one step and repeat.
- Test each corner with a light hand Place your hand on the mattress in the furthest corner, wait, and confirm the alarm clears because the pad has found movement. Repeat for the other three corners. If a corner still alarms with your hand on it, turn sensitivity up one step and start again.
- Step away and confirm the empty-cot alarm Remove your hand, stand back, and wait about 20 seconds. The alarm should return. If it does not, turn sensitivity down. Keep going until every corner is detected and the empty cot alarms.
- Repeat when you move the pad Angelcare’s install pages say to test before first use, before placing the baby in, and every time the pad moves to a different sleep space — including a Moses basket or next-to-me.
A next-to-me that is still attached to your bed will fail this test in a misleading way: the pad may keep seeing you and never alarm. Separate the furniture first. That is Angelcare UK’s bedside-crib rule, not a sensitivity tweak.
When is a ‘working’ alarm still a problem?
When it is teaching you to dread the beep more than to read the baby. The Lullaby Trust lists false alarms as a disadvantage of movement monitors: they can heighten anxiety and disturb the baby’s sleep. Which? makes the same point in its features piece and repeats the Trust’s line that there is no evidence this sort of monitoring can prevent SIDS.
CONI’s answer to that, for families who still want a simple movement monitor, is teaching: how the kit works, what it cannot do, a plan if it alarms, and basic life support. A shop-bought Angelcare pad does not come with a health visitor. If you are using one after a previous baby died, ask about CONI as well as chasing the sensitivity dial.
In shortAn Angelcare alarm means 20 seconds without mattress movement detected, not a completed breath count. Work through pause, mattress type, slatted-base board, room vibration and the four-corner test. Official records show the Lullaby Trust and Which? both flag false alarms as a source of anxiety — and both repeat that monitors are not shown to prevent SIDS.
Questions parents ask
- The alarm woke me but the baby was fine. Did the pad fail?
- Not on Angelcare’s definition. The alarm means the pad did not see mattress movement for 20 seconds. That can be a deep-sleep period with very small movement, a mattress that soaks up motion, a slatted base, or a sensitivity setting that does not match the room. Check the baby first, then the set-up.
- Should I turn sensitivity to the maximum to stop night alarms?
- A high setting makes the pad more likely to see fans, floorboards and you leaning on the cot — so it may *fail* to alarm when you lift the baby out. Angelcare’s four-corner test is how the help pages set the level: detect all four corners, and still alarm on an empty mattress.
- We use a Sleepyhead or similar nest. Could that be the cause?
- Angelcare’s North America AC117 false-alarm article says the brand does not support using a Sleepyhead with the movement monitor because it can mask movement. That is a maker position, not a Lullaby Trust product test. A nest that lifts the baby off the mattress is the same physics as a thick foam: less movement reaches the pad.
- Does a medical-device Angelcare model stop false alarms?
- CONI’s factsheet lists the AC25-1 as a medically certified mattress monitor with four sensitivity levels and a 20-second no-movement alarm. MD / CE / UKCA is a conformity class — see the MD-mark guide — not a promise the pad will ignore a fan or a memory-foam mattress.
Sources
Official pages first. If this page and the official page disagree, the official page wins.
- Angelcare UK — AC117 false alarms — checked 10 September 2026
- Angelcare UK — Bedside crib (pad detects movement, not breathing) — checked 10 September 2026
- Angelcare UK — How to check sensitivity (four-corner test) — checked 10 September 2026
- Which? — Five useful baby monitor features — checked 10 September 2026
- The Lullaby Trust — Movement monitors factsheet for CONI coordinators (November 2025) — checked 10 September 2026
- The Lullaby Trust — Baby monitors — checked 10 September 2026
This is information, not a guarantee of any payment, and not medical, legal or product-safety advice for your home. Prices and rules change; figures carry the date they were checked. Recall status comes from official records only — a product we cannot find is not a safety all-clear. Tell us if we got a fact wrong.