Dormice are well known for their habit of sleeping for much of the time. Their popular English name is thought to derive from the French word 'dormir' meaning 'to sleep'. Dormice are known to hibernate for as much as seven months of the year. At the onset of colder weather in October, the animals will select a suitable site close to the ground to build a nest. They then curl up and go to sleep until April. During hibernation, dormice slow down their bodily functions and enter a state of extreme torpor. In this state they feel cold to the touch and take some time to rouse themselves when handled. However, they do wake up periodically for a few hours at a time. They survive extended periods without food by living off stored reserves of fat laid down in the fruitful autumn months. Dormice feed high up in the trees on a variety of food. They eat flowers and pollen during the spring, fruit in summer and nuts, particularly hazel nuts, in autumn. It is thought that insects are taken too. This variety of food must be available within a small area, a requirement which limits the suitability of some sites for dormice. Dormice become sexually mature at one year old and their breeding season is from May to September. They produce between two and seven young and can raise two litters a year. The young dormice stay with their mother until they are about ten weeks old. As well as their grass-woven nests, dormice are known to use tree cavities and boxes for rearing young. They hibernate in nests built just below ground.