Do sun bears stay active during winter?
Let's be accurate as possible and think first.
yes
The sun bear is a species in the family Ursidae occurring in the tropical forests of Southeast Asia.

Sun bears do not seem to hibernate.

Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate.

It most commonly occurs during winter months.

.

The answer is yes