If your hours change week to week, most sleep advice is useless to you. "Keep a consistent bedtime" assumes you have one.

Here is a distinction that makes the problem tractable, and it costs nothing to start using.

There are three separate numbers, and people collapse them into one:

Time off duty. The whole gap between finishing one shift and starting the next. Fourteen hours sounds like plenty.

Sleep opportunity. The part of that gap you actually reserved for trying to sleep. Subtract the commute both ways, eating, the school run, the shop, winding down. Fourteen hours becomes six.

Sleep obtained. What you estimate you actually got. Six becomes four, because the doorbell went at 11am.

Write those three numbers down for one shift. The gap between them tells you what your problem actually is, and the three problems need completely different fixes:

If off duty and sleep opportunity are far apart, your issue is scheduling and errands, not sleep. No amount of sleep hygiene touches that.

If sleep opportunity and sleep obtained are far apart, your issue is interruptions and environment. That is where blackout blinds, phone settings and a conversation with the household actually help.

If off duty itself is too small, no personal habit fixes it. That is a roster conversation, and treating it as a discipline problem just adds guilt to exhaustion.

Most people who feel like they have tried everything are applying fix number two to problem number three.

Worth adding: this is a way of organising the question, not a diagnosis. Persistent fatigue that does not respond to planning is worth raising with your workplace or a clinician rather than optimising around.

Try it for one shift and see which of the three gaps is biggest for you.