void loop() {
    
    bool switchState = digitalRead(SWITCH_PIN);
    
    if (switchState == LOW && lastSwitchState == HIGH) {
        delay(50);  // Debounce delay...
        if (digitalRead(SWITCH_PIN) == LOW) {  
            sleepMode = !sleepMode;
            Serial.println(sleepMode ? "Entering Sleep Mode..." : "Waking Up...");
        }
    }
    lastSwitchState = switchState;