A children’s rights charity said prolonged periods of detention can cause children "fear, anxiety, and distress", and urged the Government to ensure the earlier release of minors put in police custody.
New Home Office figures show Devon and Cornwall Police recorded 1,107 detentions in custody of children aged 17 and under in the year to March 2024.
Children may be detained on multiple occasions through the year.
Meanwhile, 418 overnight detentions of children were recorded
The UK ratified the United Nations Convention on the Rights of the Child in 1991, agreeing the detention in police custody of a child should be used "only as a measure of last resort and for the shortest appropriate period of time".
Police forces across England and Wales recorded 62,019 detentions in custody of children aged 17 or under last year – up 13% from 54,875 the previous year.
It accounted for 7% of all 901,758 such detentions.
Nationally, 23,305 overnight detentions of children were recorded – up from 19,883 the previous year.
Violence against the person was the main reason for children to be detained, and a total of 32,288 such offences sent children into custody across England and Wales, including 467 in Devon and Cornwall.
Louise King, co-lead at Just for Kids Law and director at the Children’s Rights Alliance for England, said the charity is "very concerned" about the increasing number of times children are detained in custody overnight.
"Children who come into contact with the criminal justice system are some of the most vulnerable in society, and spending long periods of time in a detention setting designed for adult suspects causes them fear, anxiety, and distress," she added.
Ms King called on the Government to limit the initial detention period to 12 hours for children under 18, "to ensure the police routinely prioritise children and expedite the process to enable their earlier release from police custody".
Helen Lincoln, chair of the Association of Directors of Children's Services Families, Communities and Young People Policy Committee, said: "Children and young people in conflict with the law are vulnerable, many have been exposed to repeated and extended trauma, such as bereavements, family breakdown or abuse.
"Many will have mental health issues or have fallen out of fulltime education.
"They should be treated as children first and foremost, offenders second, and every effort should be made to divert children from custody, whether remand or otherwise, as this can retraumatise children and young people and should only be used as a last resort."
Meanwhile, polices forces in England and Wales conducted 3,528 strip searches on children aged 17 or under last year, which was up from 3,122 the previous year.
Devon and Cornwall Police strip searched children 25 times last year.
Strip searching does not necessarily imply nudity or exposure of intimate body parts, though it can do, and ranges from the removal of a shirt to the removal of all clothing.
A Home Office spokesperson said: "Children should only be detained in custody when absolutely necessary, and we expect that alternatives are always considered.
"This Government is introducing new safeguards for strip-searching children and young people, with changes to the statutory codes of practice coming this spring."