It turned out to be a very hot wash when the washing machine caught fire.
Firefighters were called to the incident at the ground-floor flat in Thirlestane, St Albans, at about 10pm last Thursday.
Both pumps from St Albans attended but the fire was confined to the machine and no-one was hurt.
It is thought the blaze started when wires on the washer became chaffed and sparked.
Firefighters said that this showed the risk of using such appliances overnight to take advantage of the cheaper electricity.
Two crews from St Albans were also called out to another fire at around 5am on Friday in a flat in Clarence Road, St Albans, after a man started cooking some food in a saucepan but fell asleep and it caught fire. The firefighters arrived before it had the chance to spread but the flat was badly smoke-logged.