When you are sinking in a dream, you are most likely being overwhelmed or anxious about something related to work and relationships. This sinking feeling is arises when someone or something is pulling you down causing you to stop in your path to any progress.
In the sinking dream, you are no longer in control of the situation. It takes hold of your body, and no matter how hard you struggle, you continue to sink and experience a great degree of helplessness.