I switch both the pc and the router of when I go to bed, apart from security, there's the possible fire hazard to be considered, to say nothing of the cost.
Whilst on the face of it you might think you're doing the right thing there, you should really keep the router on 24x7.
- They are designed to run 24x7 without being a fire risk
- There is very little difference to the overall security of your house whether you run them during the day or 24x7 as you will have hacking attempts every 30 seconds or so anyway.
- The cost differential of a 3 watt device over a year is insignificant
...however, the big issue is that the way the Exchange premises equipment monitors and tunes your link speed depends upon you having the device on 24x7. In fact you can lose a significant percentage of your bandwidth purely by adopting a "turn it off at night" attitude.