Are Hallucinations Due To Stress?

Hi. My name is Vijay. I m 23, an engineering graduate. Sometimes when I m in bed before sleeping, I get a weird sensation of smoothness and roughness alternating very quickly. I picture a milky white smooth texture and then suddenly a ragged rock with infinite black fractal like scratches. The textures alternate in about a second and once it starts, i can t actually stop it right away. The I realise whats happening and get out of bed and drink a glass of water, wash my face and come back to sleep. This doesn t happen that often. But it really creeps me out when it does. I thought it might be a stress reaction. But this sometimes even happen when it was a chill day.