Proverbs 14:13 Even in laughter the heart is sorrowful; and the end of that mirth is heaviness. 

‘Even in laughter the heart is sorrowful; and the end of that mirth is heaviness.’ The sorrowful heart may hide behind forced smiles and laughter, but its heaviness will eventually be revealed.

In James 4:9 backsliders are commanded to be afflicted, and mourn, and weep: let your laughter be turned to mourning, and your joy to heaviness referring to laughter prompted by sin and joy founded on sin. There are ten commands given to backsliders: Submit yourselves to God (Jas. 4:7). Resist the devil. Draw nigh to God (Jas. 4:8). Cleanse your hands, you sinners. Purify your hearts, you doubters. Be afflicted, mourn, and weep (Jas. 4:9). Let your laughter be turned to mourning. Let your joy be turned to heaviness. Humble yourself before God (Jas. 4:10). Speak not evil of one another (Jas. 4:11).