Interrupting light cycles? (i.e. 1hr off then back on)?

Lets say during veg cycle of the light needs to be turned off temporally then go back on.

For example an 18/6: the light is on 8hrs, off 1-2hrs, then back on until 18th hour.

How, if at all, would this effect the plants?

during veg, it wouldnt really do any harm, especially only an hour or so, and if only once, its fine. .