Millis (); won't work properly

Projects Programming
21 
unsigned long PERIOD1 = 25;  // interval at which to blink (microseconds) = 20 Hz
unsigned long PERIOD2 = 12.5;  // interval at which to blink (microseconds) = 40 Hz
unsigned long PERIODact = 5000;  // amount of time to keep blinking (milliseconds)
unsigned long PERIODbtn = 150;  // (microseconds)

Do i need unsigned long?