SMA HAS HDG AND ALTDEV ON VOR APCH.

Narrative

I REQUESTED A LOWER ALT TO PREPARE FOR THE VOR-A APCH INTO M37. THE CTLR APPARENTLY WAS UNAWARE OF MY IMPENDING TRANSITION TO THE APCH PHASE. AT THIS POINT I WAS WITHIN 2 MI OF THE VOR ON WHICH THIS APCH IS PREDICATED. THE CTLR INFORMED ME OF THE HOLD ON THE VOR AFTER I PASSED IT AND CHANGED HIS HOLDING INSTRUCTIONS AFTER I HAD STARTED A TURN BACK TO THE VOR. DURING THIS TURN; MY SON (4 YRS) RELEASED HIS SEATBELT AND HIS MOTHER (SITTING IN THE FRONT SEAT) STARTED TRYING TO GET HIM BACK INTO IT (BOTH HAVING A HEATED EXCHANGE). DURING THE COMMOTION; I INADVERTENTLY LEFT MY ASSIGNED ALT OF 5000 FT TO 4500 FT FOR ABOUT 1 MIN. HAVING BECOME DISORIENTED WITH RESPECT TO THE ACFT POS RELATIVE TO THE VOR; I RETURNED TO THE VOR AND RECEIVED CLRNC FOR THE APCH WHICH WAS ACCOMPLISHED SAFELY. THIS COULD BE PREVENTED BY: 1) BETTER PLT/CTLR COMS OF EXPECTATIONS REGARDING POTENTIAL HOLDS. 2) BETTER PLT CTL OF THE COCKPIT ENVIRONMENT. 3) BETTER PREPARATION ON THE PART OF THE PLT PRIOR TO TRANSITIONING INTO THE APCH PHASE.