This study [1] seems to suggest that there are quite a few negative effects that can be associated with retirement itself rather than age alone. But the effects

This study [1] seems to suggest that there are quite a few negative effects that can be associated with retirement itself rather than age alone. But the effects are rather small and it also seems like they can be offset by maintaining a social life and physical exercise after retirement. So yeah, being alone on the couch all day is bad for physical and mental health. But that holds for any age, retirement only exacerbates it for some people. [1] https://www.jstor.org/stable/27751397 https://www.jstor.org/stable/27751397