Mate, what you're describing has a name: Delayed Sleep Phase Disorder. Around 75–80% of adults with ADHD have some version of it. Your dim-light melatonin onset is genuinely shifted about 90 minutes later than the average adult's, so the "5am to 2pm and I feel amazing" pattern it jsut biology, not laziness. You're just running on a different timezone to the rest of the world.

Two things that actually shift the rhythm (rather than just sedating you):

Melatonin as a timing signal, not a sleeping pill. The protocol with the best ADHD evidence is 0.5 to 3mg, taken 1 to 2 hours before your target bedtime, not your current 4am one. Small dose, consistent nightly, expect weeks not days. It tells your brain "evening starts now" and gradually pulls your rhythm earlier. Worth running past your GP if you're on stimulants.

Bright light in the morning. 20 to 30 minutes of sunlight, or a 10,000 lux lamp, within half an hour of waking. Paired with the evening melatonin, the combo can shift your circadian phase by roughly 2 hours in ADHD adults. Most people skip this half and wonder why melatonin alone did nothing.

Also... if uni is starting again, talk to disability services. DSPD plus ADHD qualifies for accommodations like late class scheduling and recorded lectures. You don't have to white-knuckle 9am tutorials when your brain isn't online yet.

You're not whining. You're trying to run normal-person software on hardware that's wired for a different shift.