14 UNITED NATIONS STANDARD MINIMUM RULES FOR THE TREATMENT OF PRISONERS for a limited time period and as strictly required for the maintenance of security and order. Rule 44 For the purpose of these rules, solitary confinement shall refer to the confinement of prisoners for 22 hours or more a day without meaningful human contact. Prolonged solitary confinement shall refer to solitary confinement for a time period in excess of 15 consecutive days. Rule 45 1. Solitary confinement shall be used only in exceptional cases as a last resort, for as short a time as possible and subject to independent review, and only pursuant to the authorization by a competent authority. It shall not be imposed by virtue of a prisoner’s sentence. 2. The imposition of solitary confinement should be prohibited in the case of prisoners with mental or physical disabilities when their conditions would be exacerbated by such measures. The prohibition of the use of solitary confinement and similar measures in cases involving women and children, as referred to in other United Nations standards and norms in crime prevention and criminal justice,2 continues to apply. Rule 46 1. Health-care personnel shall not have any role in the imposition of disciplinary sanctions or other restrictive measures. They shall, however, pay particular attention to the health of prisoners held under any form of involuntary separation, including by visiting such prisoners on a daily basis and providing prompt medical assistance and treatment at the request of such prisoners or prison staff. 2. Health-care personnel shall report to the prison director, without delay, any adverse effect of disciplinary sanctions or other restrictive measures on the physical or mental health of a prisoner subjected to such sanctions or measures and shall advise the director if they consider it necessary to terminate or alter them for physical or mental health reasons. 3. Health-care personnel shall have the authority to review and recommend changes to the involuntary separation of a prisoner in order to ensure that such separation does not exacerbate the medical condition or mental or physical disability of the prisoner. 2 See rule 67 of the United Nations Rules for the Protection of Juveniles Deprived of their Liberty (resolution 45/113, annex); and rule 22 of the United Nations Rules for the Treatment of Women Prisoners and Non-custodial Measures for Women Offenders (the Bangkok Rules) (resolution 65/229, annex).