Water has a specific heat capacity of about 4.2 Kilojoules per kilogram per degree Kelvin, so it would take about 6 Kilowatt Hours of electricity to heat 100 Litres of water from 15 degrees centigrade to 65 degrees centigrade. As a standard immersion heater is 3KW, so it would take 2 hours to heat 100 Litres of water.
Drinking a large amount of carbonated drinks at bedtime can also cause hiccups, as the air in these drinks can distend the stomach. Consuming a large amount of alcohol before going to bed is another possible cause of hiccups during sleep. The excessive amount of alcohol can cause the stomach to distend.
They are caused by sudden contractions of the diaphragm triggered by irritation or stimulation of that muscle. Some leading pediatricians are of the opinion that infant hiccups are usually caused by feeding (breast, formula or other foods) or by a drop in temperature that causes the baby to get cold. Hiccups are considered harmless unless they prove persistent enough to interfere with regular feeding and sleeping.