Saraswati Biswokarma sits in the dark, rearranging the threadbare cotton sheet and straw bed she is forced to sleep on before bringing her knees up to her chest with a shiver.
It is already mid-morning but she has not been allowed out of the airless brick shed where she has spent every night for the past week.
The 13-year-old was effectively banished to the shed -- barely big enough to stand or lie down in -- where she must experience her first period alone in a traumatic ordeal.
"I've been here eight nights so I have one left," she says with a nervous smile. "It's not nice here, it's scary and I felt very alone on the first night. I was so scared."
Saraswati's isolation is part of a centuries-old Hindu ritual known as chhaupadi that has been blamed for prolonged depression and even deaths in remote, impoverished western Nepal.
Under the practice, women are prohibited from participating in normal family activities during menstruation and after childbirth, and can have no contact with men of the household.
"I'm not allowed to touch any cattle or go inside our house. I have to stay in the shed and when my mother calls I have to wait nearby the house with a plate so she can give me food," Saraswati says.
She is also barred from consuming dairy products or meat or taking a bath. Even looking in the mirror is frowned upon.
The practice stems from the belief that when women have periods they are impure and will bring bad luck on a whole family if they stay in the house and will contaminate anything they touch.
In 2005, the government, in line with a Supreme Court order, enacted a law abolishing chhaupadi but enforcement has been minimal or non-existent.
Saraswati's shelter, known as a chhaupadi goth, looks like a miniature cow shed, with a dirt floor and no windows or running water.
In January last year, two women were found dead in chhaupadi goths in the remote district of Achham after temperatures dropped to 30F (-1C). In another case, a 15-year-old died of diarrhoea contracted while sleeping in a shed.
Chandrakala Nepali, 17, is preparing for her fifth night in her goth.
Her parents went to Mumbai to find work two years ago, leaving her and four younger siblings to live with relatives in a house high up in the hills an hour's walk from Mangalsen, the main town in Achham.
"During the day I'm allowed out but only to work in the jungle, collecting firewood," she says, sweeping the dark, cold hut, which is barely big enough to lie down in.
"I'm not allowed to walk on the same road as the cattle and I'm not allowed to be with my family for seven days. To eat, I sit outside the house and they bring me food on a plate.
"When I'm alone in the shed I feel scared. There are insects and I'm afraid of snakes coming in."
Chandrakala says that if she has daughters she would never force chhaupadi on them.
But few women are prepared to challenge the status quo, and many continue the ritual for fear of community disapproval or out of religious belief.
Pashupati Kuwar, 30, lives with her five children in Budhakot, a small hamlet high in the hills.
Her husband is away, working in the Indian city of Pune, while her in-laws died several years ago, but Kuwar still observes chhaupadi.
"I don't touch any cattle for five days. I sleep on straw. Most of the day I go out but I go back to the shed to sleep," she said.
Pashupati says she will make her six- and 13-year-old daughters take part in the ritual.
"Some people think it's wrong but if I didn't do this my god would be angry."
Pashupati's own mother, Kunta Rawal, 45, has turned her back on chhaupadi.
"Before I thought it was important because of what I was told by elders and society but I have been made to realise that it is wrong," she says.
Nepal's education ministry is hoping to establish a literacy drive in the region, including health education classes dedicated exclusively to reproductive health and menstrual hygiene.
Thanks to campaigns by humanitarian organisations like UNICEF, the sites of confinement are beginning to improve, with women often allowed in separate rooms in the main house rather than banished outside.
Janaki Bohara, 40, president of the Bahagyaswor Paralegal Committee, a women's advocacy group supported by UNICEF, says she will refuse to allow her 14-year-old daughter to take part in the ritual.
"If I see families doing this to their daughters I will say to them 'look at me -- I have nothing to do with chhaupadi but nothing has happened to me'. I'm ready to go to villages and fight people about this issue."
Meanwhile Saraswati's 18-year-old aunt, Radhika Biswokarma, is a rare example of a chhaupadi rebel.
"After the first time I stayed in the chhaupadi goth I decided from then on I would not do it again," she said. "Society said to me 'your god will be angry' but I don't care."