Of everything patients ask me about improving sleep, the one lever people underuse the most isn't anything that happens at night — it's what happens in the first hour after waking up.
Your circadian clock, the internal timer that governs when you feel sleepy and when you feel alert, is set largely by light exposure. Bright light in the morning tells that clock "the day has started," which in turn anchors the timing of melatonin release roughly 14-16 hours later that evening. Get that morning signal reliably, and your evening sleepiness tends to arrive on schedule too.
The practical version of this is simple: get outside, or at least near a bright window, within the first hour of waking, for something like 10-20 minutes. Overcast days still provide far more lux than indoor lighting, so it's worth doing even when it isn't sunny. Sunglasses blunt the signal, so skip them for this window if you can.
What this doesn't require is any special device, app, or supplement — it's one of the few sleep interventions that costs nothing and has almost no downside. For patients dealing with delayed sleep timing in particular, I usually suggest starting here before we talk about anything else.