We found establishing a solid day-time to bed-time routine helps in the mid stages.
Daytime routines mean keeping everything on a reasonable schedule from waking up, letting in some sunshine or turning the lights up, cleaning to freshen up in the morning & eating, cups of tea +entertainment etc to keep the PWD awake & focusing, if possible during the daylight hours... Bedtime routine is the opposite: all about slowing down, getting quiet (we even talk more softly in the half hour before bed) dimming lights, warming the room, relaxing by rubbing in moisturizer etc, using a colored nightlight and saying goodnight etc.
Failing that, you could speak to the Dr if they continually act out dreams and have disturbed sleep patterns (which is common) they may be able to prescribe some medication to help sleep better.
If you're not using one already, a baby monitor can help you keep an eye on them without having to continually worry what is going on throughout the night.