The question is not trivial, and in fact we are here today to answer: consume so much to keep the modem switched on at night!
There are many ways to squander money – we know – and keep the modem turned on at night, not used, of course, is not one of these, since the waste calculated on an annual basis is absolutely low: different, however, is the case at night let the computer to download something or telephone connected to your WiFi network, while you are resting.
This behavior is to be avoided, unless you have important files to download, because in that case the modem is working and it is normal that consumption of course, do not expect some kind of monthly or annual expense, because to consume is especially the PC (and, in relation to the modem, however, consumption depends on the model and your contract with your operator).
The modem turned on at night does not consume much, in short; This does not mean, however, that there are no contraindications: the modem always on, in fact, obviously has a negative impact on the environment, and is certainly not a negligible element, given the world we live in and the problems we face world-wide; secondly, a modem always active overheats more easily: this is not a bad thing, though, because then you just do a reset and you’re done (even if doing a reset is quite annoying). Been careful only to the power supply, because if running continuously, it could burn, with all the damage that would result.
It goes without saying that, even if a modem consumes little turned on at night, it does not mean that consumption is not for nothing: the cost is minimal, but there is and, therefore, if you are set with the savings, you should turn it off and turn it on when you need it.