[jtonz]

I would add another thing that you suddenly have a less clear agenda or daily goals to achieve.

Working as a IC you often have a backlog of work provided by someone else where it is their job to prioritise and structure that work for you. Moving into a management role it becomes your job to find and prioritise your own tasks.

It is very easy to feel like you aren't contributing or completing productive work as your workload and goals are now completely self defined.