Trainticketdeliver.com not only provides train ticket to Lao Cai / Sapa but also offers transfer service from Hanoi airport to Hanoi Train station to take the overnight train to Sapa.

Discover  Lao Chai - Ta Van - Giang Ta Chai / Cat Cat – Sin Chai
Day 1: Sapa – Lao Chai – Ta Van – Giang Ta Chai                                                                                                    
Day2: Cat Cat & Sin Chai - jeep to Lao Cai station

The trains from Ha Noi to Lao Cai /Sapa run nightly and arrive early in the morning or vice versa (normal departure time  from 20h15 - 21h55 from Hanoi and arrive in Sapa about 5h00 next day