Only if you are on a time-of-use tariff such as Economy 7. On a standard tariff the rate is identical at three in the morning and at six in the evening.
- Standard tariff: one rate, all day. There is no saving from moving usage, only the risk of running a machine unattended.
- Economy 7 or a smart time-of-use tariff: the night rate can be a third of the day rate, and moving the washing, the dishwasher and any immersion heating into that window is one of the few genuinely large savings available.
- Check which you are on before changing your habits. It is on the bill.
- If you have an electric vehicle or a heat pump, a time-of-use tariff is usually worth moving to.
Do not run a washing machine or tumble dryer overnight while everyone is asleep. Both are among the commonest causes of domestic fires, and a smoke alarm is far less useful when the fire has an hour's head start.
The cap sets a single rate for standard tariffs, and suppliers have no mechanism to vary it by hour. Only a metered time-of-use tariff creates a cheaper window.
Energy figures are worked from the Ofgem price cap on the date shown and from typical power for the appliance class, not from a named model. Your own rate and your own rating plate are the ones that count. Full disclaimer.