org-cycle-emulate-tab

org-cycle-emulate-tab is a variable defined in `org.el'.
Its value is

t

Documentation:
Where should `org-cycle' emulate TAB.
nil Never
white Only in completely white lines
whitestart Only at the beginning of lines, before the first non-white char
t Everywhere except in headlines
exc-hl-bol Everywhere except at the start of a headline
If TAB is used in a place where it does not emulate TAB, the current subtree
visibility is cycled.

You can customize this variable.