Your beardie will actually benefit from a good drop in temperature if it's presently healthy. Anything down to 65 is just fine and can even go a little lower without any problems. Beardies need this drop in temps and they also need a dark place to sleep at night.
You can get a timer from any home improvement store that will turn the lights off and on automatically.
BTW, I know what you mean when it seems the beardie is cold. It just doesn't seem right since we don't get that cold but remember these are cold blooded animals and obtain the temperature of thier environment. In the desert, where they are native to, it gets cool in the evenings so this is totally normal. Maybe hard to accept but believe me it is completely normal for them to be cold in the morning.
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Rob Talkington