Our brains are not adept at switching from one task to another. When we do this we lose up to 40% of our work time. Try working in blocks of time. This could be 45 minutes or two hours – whatever suits you. This is called focused 'mono-tasking' and you'll enjoy the feeling of satisfaction of getting tasks completed faster!
So what, now what? Turn off all notifications for at least one long block of work time every day.