LED blinks faster in darker environments.

Code:
int photoval = 0; // variable to control pulse speed
int photoPin = 2; // pin to read pot
int ledPin = 13; // green lead connected to dig. pin 9
int time = 0;

void setup()
{
pinMode(ledPin, OUTPUT); // sets the digital pin as output
Serial.begin(9600);
}

void loop()
{
photoval = analogRead(photoPin);

Serial.println(photoval); // prints another carriage return

time = map(photoval, 0, 1023, 2000, 0); //brightness - ambient light 0-1023

digitalWrite(ledPin, HIGH); // sets the LED on
delay(time); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(time); // waits for a second
}