"The Science of Sleep" _ Michel Gondry’s film is pure whimsy presented with a childlike lack of guile yet piled on so thickly the movie becomes less a story and more an exercise in caprice for its own sake. Writer-director Gondry’s tale of a man-child (Gael Garcia Bernal) seesawing between his harmlessly demented fantasy world and a stifling outer life is filled with clever, dreamy visuals. But the emotionally stunted hero feels as artificial as the makeshift props Gondry weaves into the man’s weird alternate reality. Bernal plays a man whose vivid dreams of a cloistered personal world gradually are taking precedence over the drab future shaping up in his real life. He finds a potential anchor to draw him back to the conscious world when he develops a sweetly chaste kinship with a new neighbor (Charlotte Gainsbourg).