B777 Landing lights in 'dim mode'

[dv8]

Have noticed when passing in the cruise a 777 the landing lights are dim but on.

The only ref I find in the FCOM is:

An automatic dim function illuminates the lights in the dim mode when the wing landing lights are selected ON and landing gear are up.

But this cant be it as the lights switches would be OFF during cruise. So there must be a 'very dim mode' for when the switch is off and gear is up.

But the main purpose of my question is what is this for? Heat shock protection or anti fogging/icing are only guesses but would appreciate a factual answer.

Thanks

[nitpicker330]

Same on the 787 and 748