The effects of add-on prolonged-release melatonin ( PRM ) ( @ mg ) to standard therapy on cognitive functioning and sleep were investigated in @ patients ( men -LSB- @ % -RSB- , women -LSB- @ % -RSB- , average age @ years -LSB- range , @-@ years -RSB- ) diagnosed with mild to moderate AD , with and without insomnia comorbidity , and receiving standard therapy ( acetylcholinesterase inhibitors with or without memantine ) .