We appreciate that there are some people who find it hard to stay warm in the cold winter months and with the cost of living putting pressure on some households, we wanted to take a look at some thermal underwear this week. So Sophia Smith has a 7 Day Challenge for us and begins with these Marks and Spencer thermal heatgen plus leggings. Come back tomorrow for Day 2 of her challenge and at the end of the week she'll conclude with picking the best from all 7 items reviewed. Filmed in 4K.

"There were 3 stages of warmth and extra warmth I think is their highest one." Sophia Smith