I would like to cross the border between Thailand and Laos at Chiang Khong - Huay Xai, and I saw there are buses - direct or not - between Chiang Mai and Chiang Khong.
To save some time, I'd like to ideally get a direct overnight bus between Chiang Mai and Chiang Khong.
The Lonely Planet and wikivoyage mention some direct buses, twice daily but there are no details about whether they are overnight or not (I am afraid not since the duration is about 6 hours).