SilentSleep Thermal Blackout Curtain

This one's less about a perfect seal and more about an all-round upgrade if you already have curtain rails. The thermal lining does a genuinely noticeable job of keeping the room cooler in summer and warmer in winter, plus a small amount of external noise reduction — handy if traffic or neighbours are part of what's disturbing your sleep alongside light. It won't block light as completely as the frame-fit options, but paired with an eye mask it's a comfortable, low-effort setup.