Wolf attacks are incredibly rare whereas bear attacks are more common. Typically wolves are afraid of humans and will actively avoid contact. Humans are the predator typically in wolf encounters so they are much more afraid of us than we of them.
That said wolves have been known to attack humans, normally when driven by hunger or disease (rabies). When they attack humans they will generally only attempt to attack children under the age of 18.
A worldwide 2002 study by the Norwegian Institute of Nature Research
showed that 90% of victims of predatory attacks were children under
the age of 18
A fully grown adult should have nothing to fear from wolves.
Are there any precautions that can be taken against wolves, especially
during the winter, to make sleeping safe?
It's very very unlikely that a wolf will wander into your camp, rip though your tent and attack you. Your biggest chance of encountering a wolf is for you to (inadvertantley) go to it. A wolf will stay well clear of a human camp. If on the very low chance that a wolf is driven by hunger into your camp it will want to eat what scraps it can and get away. You could mitigate this risk by keeping food in sealed containers.
especially during the winter
Winter is actually the safest time, wolves are actually more likely to attack in the summer, when they have hungry pups to feed and food pressure is much greater.
PS I'm very jealous that you saw a wild pack of wolves. Wolves were (unfortunately I think) killed off in the UK a long long time ago.