Which of the following represents the earliest manifestation of Cushing 's syndrome?

Normal plasma coisol level is 5-20 mcg/dl in early morning which is reduced to less than half by 11pm. Loss of this diurnal variation is the first characteristic change in cushings syndrome and is usually observed in children above 3years. Ref: Harrison's Internal Medicine, 18th Edition, Pages 2897, 2945 ; Pathophysiology of Disease: An Introduction to Clinical Medicine, 6th Education, Stephen J. McPhee, Chapter 21 ; Pediatric Endocrine Disorders By Desai, Meena P, Page 232 ; Diagnosis and Management of Pituitary Disorders By Brooke Swearinge, Pages 164, 192