Doing another MSc during PhD I've been a PhD student in a STEM field for less than year now. Before embarking on this journey, I was pondering between electrical engineering and computer science for my MSc studies, which I completed before starting a PhD (It was possible to branch from BSc to either field). However, even after completing a MSc degree and working on a PhD in electrical engineering, I still find myself intrigued by the field of computer science. 

Would I be spreading myself too thin / hindering my PhD project severely if i started working on a master's degree (2 years) in computer science as a free-time hobby during my PhD studies? I have already completed some coursework related to the degree and there is some synergy between the fields.

I have a strong feeling that studies in computer science would be valuable in my future career. On the other hand, I do not know if I will have to increase my working hours on the PhD project at some point to the extent that I don't have sufficient "free-time". 

I would like to hear if you have had similar experiences/plans and what did you do. thanks for reading!
Would I be spreading myself too thin / hindering my PhD project severely if i started working on a master's degree (2 years) in computer science as a free-time hobby during my PhD studies?


Everything else being equal and all things considered: YES! Unless you are specifically doing a part time PhD, a PhD is a full time job and there normally shouldn't be enough free time to take on master's level study in another subject. If you were my PhD student and you came to me with the idea of doing extra study unrelated to your PhD project, I would tell you it was a distraction from what you should be doing and could very likely lead to your PhD taking much longer than either you or I want it to. If you told me that you had a large amount of free time that you want to fill with academic study, I would help you find ways to apply that time toward your PhD so that you might advance faster on it.

Perhaps the best thing to do is to bring this idea to your supervisor and see what they think. They know you and your project, they will know if you are not being realistic about your available time.