How to decrease property values incrementally?

Experimenting this time with multiple instances like 'Beam', 'SurfaceGUI', 'TextLabels', and 'PointLight'. Code below works properly, just not sure how to go about using the 'for' loop making it so that each activation (or deactivation) makes the instances fade in or out.

--Setting some variables here and should be alphabetical--

surface = script.Parent.Parent.Surface
root = script.Parent.Parent
base = script.Parent
light = root.Emitter.p1
text0 = surface.G0.T0
text1 = surface.G1.T1
b0 = root.Emitter.b0
b1 = root.Emitter.b1

--Add a debounce here plus some extras--

local isOn = false
local debounce = false -- For later use...

--All the fancy stuff down here--

function holo()
	if isOn == false then
		print("Turning on...")
		wait(2)
		isOn = true
		b0.Enabled = true -- All '.enable' lines self-explanatory, open to future optimization
		light.Enabled = true 
		b1.Enabled = true
		text0.TextStrokeTransparency = 0
		text0.TextTransparency = 0.3
		text1.TextStrokeTransparency = 0
		text1.TextTransparency = 0.3
	elseif isOn == true then
		print("Already on, turning off...")
		wait(3.5)
		isOn = false
		b0.Enabled = false -- All '.enable' lines self-explanatory, open to future optimization
		light.Enabled = false 
		b1.Enabled = false
		text0.TextStrokeTransparency = 1
		text0.TextTransparency = 1
		text1.TextStrokeTransparency = 1
		text1.TextTransparency = 1
		print("Off")
	end
end

script.Parent.ClickDetector.MouseClick:connect(holo)

Here’s a simple loop that should work changing the .Brightness from dim to bright. Its just a for loop where “i” represents the brightness of the part. The 0 is the min brightness and 5 is the max. It is set to increase and decrease from 0-5 and 5-0 in increments of .1. Obviously you can change these values depending on what effect you're trying to achieve. Hope it’s helpful!

local light = script.Parent -- if it’s in the part
while true do
    for i = 0,5,0.1 do
        light.Brightness = i
        wait(1)
    end
    for i = 5,0,-0.1 do --This should be a neg num telling the loop that it is decreasing i.
        light.Brightness = i
        wait(1)
    end
end