My ps4 keeps turning off mid-game and I don't know why. Please help.

I've had my ps4 since it's been released, and haven't had any problems with it until now. However for the last 3 months my ps4 has been turning off seemingly randomly and most of the time mid game. Sometimes it makes a low pitched beeeeeeeeeep sound when it turns off. But every time the blue light stays on and the fan continues running but the controller turns off as if I turned the ps4 off or put it into rest mode. I haven't cleaned it since I bought it and I've also learned how to replace thermal gel (haven't done it yet though) is it worth it to take all apart and clean it and replace the thermal gel? From what I've heard this isn't normal when the ps4 overheats so it may be a different problem entirely.

Any insight would be greatly appreciated.