Why on earth do you want to 'sleep' while computing anything? Sleeping for any time is nearly always a bad idea in any language. It essentially tells the thread to stop doing anything for that period of time.
So, in a language like javascript that only has one thread (forgetting 'web workers'), what benefit would you reap for pausing ALL computation? It's a bad idea, forget it.
Now to the problem that you've written, though I don't think this is your actual problem. Why do you want to pause for a second while computing this sequence? Even to compute the first 6 numbers in the sequence, it's going to take 8 or so seconds. Why? What possible reason is there to pause for a second between recursive calls? Stop it. Remove it.
If you want to just yield the final result a second after it completes, then use setTimeout with a function uses the answer in some way.
function fib(n) {
...
result = fib();
...
setTimeout(function() {
console.log("Fib for " + n + " is " + result);
},1000);
}
Do not try to implement 'sleep'. Do not pause during computation.
