SleepNumber Integration keeps needing the password entered

### The problem

Every other day or so, SleepNumber integration fails and needs me to re-enter my password, that lasts for a day or two, and then the same thing again.

### What version of Home Assistant Core has the issue?

core-2026.9.1

### What was the last working version of Home Assistant Core?

core-2026.8.X

### What type of installation are you running?

Home Assistant OS

### Integration causing the issue

SleepIQ

### Link to integration documentation on our website

https://www.home-assistant.io/integrations/sleepiq

### Diagnostics information

From the log:

Logger: homeassistant.components.sleepiq.coordinator
Source: helpers/update_coordinator.py:543
Integration: SleepIQ (documentation, issues)
First occurred: 1:28:40 PM (1 occurrence)
Last logged: 1:28:40 PM

Authentication failed while fetching {EMAILADDRESS}@SleepIQSleepData data: API call error response 401 >

### Example YAML snippet

```yaml

```

### Anything in the logs that might be useful for us?

```txt

```

### Additional information

_No response_

Start with the SleepIQ integration's coordinator and the helpers/update_coordinator.py location shown in the log, then trace how the 401 response leads to repeated password prompts. Reproduce the failure across the token lifetime and compare behavior with core-2026.8.X; done means authentication remains valid for more than a day or two without manual re-entry, with regression coverage for the failure.

Written by the indexing model from the issue text.