Putting the CC2541 to sleep
How do you interface with this chip? It seems to have three power modes which you can configure:


Power Mode 1 (4-µs Wake-Up): 270 µA  
Power Mode 2 (Sleep Timer On): 1 µA  
Power Mode 3 (External Interrupts): 0.5 µA


Maybe this user guide may help you:
http://www.ti.com/lit/ug/swru191d/swru191d.pdf