1. A directly conceived object of thought
2. Functioning of a new product or innovation.
What happens is that your roof covering be it tiles or metal roofing radiates heat into the roofspace, tiles absorb and retain heat for long after the sun goes down radiating heat into the roofspace and I myself being a roofer know that metal roofing gets so hot you can hardly stand on it imagine the heat from metal roofing radiating into the roofspace. Sure you have insulation however after 4 days of excessive heat from the summer sun the insulation loses its integrity and allows all the heat locked into the roofspace to invade the inside of the home, yes now you are hot and just imagine how much sleep you are going to get tonight.
The answer to your problem is effective roofspace ventilation and I mean effective.
You can pay a fortune for the wrong kind of roof ventilation but no price whether it be cheap or expensive will be of benefit if it is not effective.
For effective roof ventilation that does work very well for cooling the enclosed space (the inside of the home) you should only consider Universal Ventilation for your roofspace. Having inlets and outlets for fresh air to flow throughout your roofspace. You will have a great night sleep