Why is Minecraft suddenly making my laptop screen go black every time I play it now?

Every time I play Minecraft (since yesterday, at least), my screen eventually goes blank and I can’t do anything about it other than turn my computer off and back on again. I haven’t had this problem at all before yesterday, and I haven’t changed anything about my computer. It has happened on every video setting, and it is becoming more frequent.

What is causing this, and how can I fix it?