now if you have your Youview in Smart standby mode the default times for it to go into Deep Sleep mode are between 1am and 5am. it will take several minutes to reach deep sleep which might explain your 1:05am experience.
Are you watching on your TV rather than on your Youview box ?
If so is your aerial feed fed to the Youview box and then passed thru to the TV ?
If it is then when your Youview box reaches deep sleep the pass thru will not occur and the TV will receive no signal.
IF that is the scenario then you can elect to watch the Freeview program on your Youview box ,or you can change the default time for the Youview smart standby see
you could also consider changing the standby mode on the Youview box to the less energy efficient Allways Ready or you could if your Freeview signal is suffiently strong splitting it so the Youview box and Tv are fed separately.