C#等待1秒

是否有像睡眠(秒)这样的功能,但它不会阻止UI更新？
我有一个这样的代码,如果我把线程睡眠后(letters.Children [Words [index] .index]作为TextBlock).Text = Words [index] .LetterCorrect; (之后我想睡觉)它只等待1秒然后UI获得更新,但我不想要那样.

private void Grid_Click(object sender,RoutedEventArgs e)
{
    if (index == Words.Count() - 1) return;
    if ((((e.Source as Button).Content as Viewbox).Child as Label).Content.ToString() == Words[index].LetterCorrect)
    {
        (letters.Children[Words[index].index] as TextBlock).Text = Words[index].LetterCorrect;

        letters.Children.Clear();
        LoadWord(++index);
        this.DataContext = Words[index];
    }
}