This depends on the network that you are in. If you're not sure of your network, then a useful way to figure this out is using our power cuts page, where we note the networks for each part of the country.
Below are the standard times for each network, but there are sometimes special plans were the time differs, like our Electric Car plan.
For Orion & Electra Networks
In these networks the 'Night' period is 9pm - 7am, and the 'Day' period is 7am-9pm
For all other networks
In these networks, the 'Night' period is 11pm-7am, and the 'Day' period is 7am-11pm
If you're not sure which is correct for you, then get in touch with us.