No power to centre dash console lights, Nav, CD, for split second. Then resests.

New to this so please excuse any glaring mistakes. Purchased 3 yr old Insignia 2 yrs ago and have been very pleased with it. Has now clocked up 82k (last 25k with me and mainly on motorways). Always been regularly serviced, etc. But when on the M25 at 5am yesterday morning, the centre dashboard + CD/Radio + Sat Nav suddenly shut off. Everything else worked, no engine issues, no ECU warning lights.
All reset and back to normal within 2 minutes but same thing happened on the way home several hours later. Again, only a temporary loss of power but enough to reset the SatNav.
Sounds like an electrical issue -maybe a power cable but any thoughts/advice gratefully accepted.