Why one hour does so much damage
Adults absorb the clock change with a coffee. Toddlers do not, and the reason is simple: they run on a body clock, not a wall clock, and the body clock does not know the clocks changed. When the clocks go back, a toddler who woke at 6am now wakes at 5am, is ready for bed an hour before you want them there, and is overtired by the time the new bedtime arrives. Overtired toddlers do not fall asleep faster. They fight harder.
So the problem is not the hour. It is that for about a week the child's internal timing and your household timing disagree, and bedtime is where that disagreement turns into a fight.
The 5-night reset
Nights 1 to 4: move everything in small steps
Bedtime, nap and meals all shift together, ten to fifteen minutes a night, towards the new time. If you can start four or five nights before the change, the body clock arrives on the day already adjusted and there is nothing to fix. If the clocks have already changed, do the same steps afterwards. It works; it just costs a few early mornings first.
Meals matter more than parents expect. A toddler who eats breakfast at the new time will start waking for it at the new time within a few days.
Use light as the lever
The body clock moves on light. Bright light and outside time in the morning, at the time you want the day to start, pulls the clock forward. Dim light from an hour before bed lets it drift towards sleep. Blackout blinds earn their money in these weeks: an autumn sunrise at what the toddler's body calls 5am is the single biggest cause of the early wakes.
Keep the routine identical while the times move
Bath, pyjamas, two books, the same goodnight line, in the same order every night. When the times are moving, the routine is what tells the toddler's brain that sleep is coming. This is not the week to introduce a new bedtime rule or drop a step because you are tired.
For the 5am wake: dark and boring
They will wake early. Keep the room dark and the interaction minimal until the time you want the day to begin. No breakfast, no screens, no lights. This feels harsh on day one and it is what resets the clock by day four. Starting the day at 5am because the child asked simply teaches the body that 5am is morning.
Nights 2 and 3 are the worst
Expect it. The body is halfway between times and nobody is at their best. Do not respond to a hard night by adding a new rule, a new bribe or a later bedtime to "tire them out." Boring consistency is the fastest way through, and the fastest way is about five nights.
When it turns into a bedtime battle
The clock change does not create bedtime battles. It reveals the parts of bedtime that were already held together by goodwill. A toddler with less capacity meets the same small limits, one more book, lights off, stay in bed, and now fights each of them.
The answer is the same as any other limit: say it once, name the want, hold it through the protest, reconnect after. "You want another book. Two books is the rule. Goodnight." Then leave, and come back calmly if needed, without adding to the conversation. A toddler who learns during the clock-change week that the bedtime limit holds even when they are tired has learned something that lasts well past the week.
The wind-down in your pocket
The Better Parent Everyday app has a lesson called Bedtime without the battle, which walks you through the wind-down runway, the goodnight line and what to do when the protest comes, in three-minute chapters. On iPhone it can also set a wind-down alarm that starts the routine at the right time each evening, which during a clock change is worth more than it sounds. Start the bedtime lesson.