Anecdotally, I find even dedicated heavy lifting (1-1.5 hours) does not improve my sleep but similar durations of high-intensity cardio (45 minutes+) heavily improve my sleep even comparing for differing work-related stress baselines. I alternate lifts/HIIT,Tabata and do this regularly (2+ years of 5-6/week workouts) and still have reduced sleep latency times compared to before dedicated regular work-outs. My job is 100% sedentary desk job as well. Dunno if that helps.