Hello everyone! I am new to this forum and I hope this is posted in the right area. If not please forgive me.

I am travelling to Beijing China. I am leaving San Francisco Airport at 11:00 AM and arriving in Beijing at 3:15 PM.

During my flight, will there always be light outside, or will there be an opportunity of darkness.

Sorry for my dumb question, I am just kinda confused with the whole time difference. I am going to need to sleep and I am worried it will be sunny the whole time.

Thanks.