Since I am pagan I used to celebrate the solstice. People in my country does not do this because Christmas is put about where the solstice is. No other celebration was put where summer solstice is so my people celebrate that a lot!
Anyway, I used to celebrate all the passings of the year. But I cannot be bothered anymore. When I was young I could put myself (and whomever wanted to join) in my little bubble. I don't know how to do that anymore, so I simply cannot celebrate the solstice because everyone's Christmas is getting under my skin. It really stresses me out. And ruins what celebration I might have.
Winter Solstice (Or summer if you are in the southern hemisphere) is the 21 December.
That day, sun sets at 2:40 PM where I live. For me here in Europe it seems like the longest night is from 20 Dec, by 1 second compared to the night after.
According to myths, you can speak with the dead on this night. Animals will also be able to talk to you, in your language.
Some people here, say that by tradition that stuff happens between the 12 and 13 December, and that it is also important not to fall asleep during that night because
If you wake, or wake up normal, we celebrate that here with light processions and coffee and Christmas bun in bed. Or the light celebration is standardized and happens later that day. It happens on TV, in schools, daycare etc.