7,200 stone steps and 4,600 feet of elevation gain, so there was a lot of sweating during the 4 hours of climbing in early August. If you want to go light, you can purchase food and water as you climb (it gets slightly more expensive the higher you go). You can even rent heavy parkas at the top as you wait for the sunrise, as it's quite chilly up there around dawn.
My partner and I started around midnight and had no trouble reaching the top before sunrise. We were moving fast and passed many people. You'll see all different sorts of people on the path, old and young, making their pilgrimage and paying respects. Steps are very narrow (maybe 4 or 5 inches across in some areas) and steep. Plenty of infrastructure, food, and water.
Some moments were incredibly surreal as we climbed through the night. You'll see many shrines & temples with incense smoke wafting around the candles and incandescent lights, senior age people selling snacks & water bottles, everyone struggling together to keep going up the steps. If you enjoy hiking at night, and the single minded zoning out that comes with that, in addition to constant heavy breathing and sweating, I couldn't recommend it enough.
If you choose to go up before sunrise, it's a good idea to have your arrangements already made for the following night. That way you can take it easy the rest of the day after coming back down, take a nap, etc.