What is the correct way of keeping a Task alive and all Subscriptions active without spinning?

Question

I have the following TPL Task

public abstract class AggregatorBase : IAggregator
{

    public void Start(CancellationToken token)
    {
        var parent = Task.Factory.StartNew(x =>
        {
            Aggregate(token);
        },TaskCreationOptions.LongRunning, token);

        parent.Wait();
    }

    public abstract void Aggregate(CancellationToken ct);
}

within the Aggregate method implementations I have a number of Observable.Subscription's ending with the following

   public override void Aggregate(CancellationToken ct)
   {
            this.observables.Subscribe(// Do stuff);
            this.observables.Subscribe(// Do more stuff);

            while (!token.IsCancellationRequested)
            {
                System.Threading.Thread.Sleep(1000)
            }
   }

Question is whats the best way of keeping the Task alive and all Subscriptions active without spinning?