The reasons why a hamster might be less active could include the following:
Personality Factors
Some hamsters are naturally quiet and not keen on moving around. This is just part of their inherent nature.

Environmental Factors
Hot or cold weather can impact a hamster's level of activity. Both high and low temperatures can cause them to cut down on their movements to regulate their body temperature.
Health Problems
If a hamster gets sick or injured, it will also become less active. Observe whether there are other symptoms such as a lack of appetite, difficulty breathing, etc.
Stress Reactions
A new environment or a new cage might make a hamster feel nervous, leading to a decrease in its activity.
Over - exhaustion
If a hamster keeps running on the exercise wheel all the time, it may become extremely tired. Appropriate steps should be taken to reduce its activity level, giving it enough time to rest.
Countermeasures
- Provide a Suitable Environment: Make sure the hamster's cage has sufficient warming measures. For example, line it with wood shavings or cotton to help the hamster adapt to low - temperature conditions.
- Monitor Health Conditions: If a hamster remains inactive constantly, it might be ill. Check for other symptoms like a poor appetite or labored breathing, and contact a veterinarian in a timely manner.
- Ensure Adequate Rest: Appropriately reduce the hamster's activity level to let it have enough time to rest and relax.
Through the above analysis and suggestions, you can better understand and take care of your hamster, ensuring its health and happiness.