The lift to her eighth-floor apartment often stops, the lights go out and sometimes the pumps maintaining pressure in the gas central heating fail. She has a big rechargeable battery pack to keep appliances going, but it costs €2,000 (£1,770) and it only lasts so long. Her husband Ievgen, a lawyer, often has to work by torchlight. Their two-year-old daughter Katia plays by candlelight too.

Amid air raids and cold darkness, Oksana says she and Ievgen worry constantly for Katia. "I can't describe with words the animal fear when you take your child to the shelter during the explosions. "I have never felt anything like that in my life and I wouldn't want anyone to feel anything like that. The thought that she might be scared because there's no light - this is terrible."

All across Ukraine, families are bracing themselves for even tougher times ahead - a long, cold winter in which Russian President Vladimir Putin attempts to finish off his invasion by striking Ukraine's power supplies and networks. Just last weekend, a massive drone and missile strike left much of the country for a time without power. Ukrainians are now enduring regular power cuts of up to 16 hours a day.

In winter, temperatures in Ukraine can plummet as low as -20C. One senior government figure told me they expect the next few months to be brutal. "I think it will be the worst winter of our history," says the official. "Russia will destroy our energy, our infrastructure, our heating. All state institutions should be prepared for the worst scenario." Maxim Timchenko, the chief executive of DTEK, a large private energy company in Ukraine, says: "Based on the intensity of attacks for the past two months, it is clear Russia is aiming for the complete destruction of Ukraine's energy system." (BBC)