is it safe to leave my phone on all night ?

Question

will leaving my phone on all night cause it to functionslowe and hurt the battery life 

Answer 1

My phone is almost always on, 

but it is also connected to a charger most of the time. 

It seems OK.   

Answer 2

It's not an issue for my phone, nor has it been a problem for any of the phones I have owned since 1992.