Try using a timer:
Timer sleepTimer = new Timer(20000); //Creates a timer for sleeping
public MyClass()
{
sleepTimer.Elapsed += new EventHandler((s, e) => WakeUp());
}
private void BtnSleep_Click(object sender, EventArgs e)
{
if (PgbSleep.Value <= 250)
{
int temp = PgbSleep.Maximum - PgbSleep.Value;
if (temp + PgbSleep.Value >= 300)
{
Timer2.Stop();
sleepTimer.Start();
}
}
else
{
MessageBox.Show("Your pokemon is not tired enough to sleep! try playing with it");
}
}
private void WakeUp()
{
PgbSleep.Value = 300;
Timer2.Start();
}