This might be silly and I think I know the answer but - should I leave the heat lamp on all night long for my chicks? Will they sleep as they should if it is not dark?
		
		
	 
Short answer yes. 
	
		
	
	
		
		
			do they need the lamp at night even in the house?
		
		
	 
Short answer yes.
Long answer to both of you:  Chicks need heat, and it needs to be available to them on an as needed basis.  That means:  it needs to be adequate to warm them up, but the rest of their environment needs to be cool, at ambient temperatures.  Chicks that are in down are not able to self regulate their temperature.  Too warm, and they get sick.  Too cold, and they get hypothermic.  Far more chicks are killed from too much heat than are killed from being too cold.  There needs to be a spot in the brooder that is just big enough, and just warm enough for them to cuddle in that heat to warm up.  It's absolutely imperative that the rest of the brooder be cool.  And the brooder needs to be big enough that they have plenty of room to self regulate.  At least 1 s.f. of open space/chick in the first 2 weeks, and then increase to 2 s.f./chick after that.  
While the standard heat lamp protocol is to start at 90 - 95* the first week, and decrease 5* every following week, many of us have found that chicks do much better with less heat.  After the first 2 - 3 days, you'll find that they do not need any where near as much heat as the protocol recommends.  Your goal at this point is to decrease the heat to what ever level meets their needs.  If you let the chicks guide you, you'll find that the 5* rule = too much heat.  Starting at week 2, you can turn their heat off for increasingly longer periods of time.  By week 3, they should be able to go all day w/o heat if the temp is >/= 70*.  By week 4 in the summer, and week 5 in night time temps that can go down to freezing, they should be completely weaned from heat if they have a dry and draft free coop.
Many of us never use heat lamps, and have found that heating pad brooding is much safer, more natural, and allows the chicks to self regulate without the worries of the brooder becoming overheated as it will with a heat lamp.  There are also other options that some are having success with:  Wool hen and huddle box.  You can do a topic search to read about these wonderful options.  For myself, I will never use a heat lamp again, unless I find myself brooding more than 50 chicks at a time.  I brooded 48 chicks with heating pads in a coop this spring with night time temps down into the 30's.  They self weaned by 4 weeks of age.