With the 3 temperature levels I get along well, mostly I currently use stage 3 and 2. FIG.
Level 3 for heating and soaking my tired muscles and when reading in bed, step 2 thereafter made for the next 2 hours of sleep, then.
About the Wärmeunterbett I drew 2 Fitted Sheets: 1, so to speak "stationary" - directly through the Sanitas SWB 50 - that reliably "place" holds the lower bed and prevents it from sweating. That will not change every time. In comes a second fitted sheet which is changed with the other linens every time. Considering that the Wärmeunterbett in its "lifetime" should be washed only about 5 times (eg 1 time per year in 5 years), so that's I think a good idea.
Lately I use it with a mechanical / analog clock, take my bed nice and preheat off to 2 clock.
The cost switches from the hardware store do sometime unpleasant noise, ticking, clicking sound in the bedroom .... of course unbearable.
I then extensively browsed the net for analog / mechanical switches, which make no noise (Thanks for the reviews !, especially the aquarium).
The timer THEBEN TIMER 26 works well and quietly, I can highly recommend it. Costs around 16 euros.
A digital is far too fiddly.
Especially when you want to set times other times.
Should the Wärmeunterbett weaken future, I change the review.