First week with a new Spaziale Dream T and really enjoying the new machine. My goal is to wake up in the morning and be able to pull a couple of shots almost immediately. I'm using the timer function to give the machine a good hour to warm up before I wake up. I'm wondering if there is any downside to leaving the portafilter In the machine overnight so that it is also warm and ready to go. Any downside to doing this? Leave it in there locked in like you are going to pull a shot or loosely? Is a machine like this meant to be left on 24/7 or close? Any downside to that aside from power consumption? Thanks for the help.

No problem doing any of that. Machine at that level are fine being left on for longer periods, or all day.

You might be constantly putting pressure on the seals... but that might not be a real issue..

I lock my portafilter slightly loose... (not all the way)
Just to ensure it doesnt really put pressure on the seals

The only problem I've found is one time my wife went into the kitchen in the middle of the night for something, brushed by the machine and knocked the portafilter handle loose. Portafilter falls onto drip tray, then onto the floor. Wife screamed, woke the whole house up.

But no, there shouldn't be any problems. I use a TP-link smart plug with my machine, put the portafilter in the group the night before and the milk jug in the fridge, and in the morning all is ready to go when I wake up.

I recommend not tightening the portafilter in the group but rather loosely just setting it in there. That will be sufficient to preheat the portafilter but will prevent extra wear on your gasket, especially if you're doing it every night.

If you are worried about leaving the portafilter in over night you can always just warm the portafilter basket on the cup warmer. All though there is no reason to be worried about leaving it in over night. I do. The extra thermal mass from heating the whole portafilter is going to be better if you need to rinse it out if you make more than one shot in a row for the wife or what have you.

All though I just zap it with some hot water afterward if I need to rinse. I usually just wipe if the puck comes out nicely.

Be careful with it.
As @TheJavaCup77 said, lock your portafilter slightly loose. If you put too much pressure, it'll end it damaged.

Thank you for the advice. I left the portafilter lightly in the group and had the timer set to be warmed up and ready to go for when I got home from work and it worked perfectly.