12 39. Turning to the interrogation process, the CPT considers that clear rules or guidelines should exist on the way in which police interviews are to be conducted. They should address inter alia the following matters: the informing of the detainee of the identity (name and/or number) of those present at the interview; the permissible length of an interview; rest periods between interviews and breaks during an interview; places in which interviews may take place; whether the detainee may be required to stand while being questioned; the interviewing of persons who are under the influence of drugs, alcohol, etc. It should also be required that a record be systematically kept of the time at which interviews start and end, of any request made by a detainee during an interview, and of the persons present during each interview. The CPT would add that the electronic recording of police interviews is another useful safeguard against the ill-treatment of detainees (as well as having significant advantages for the police). 40. The CPT considers that the fundamental safeguards granted to persons in police custody would be reinforced (and the work of police officers quite possibly facilitated) if a single and comprehensive custody record were to exist for each person detained, on which would be recorded all aspects of his custody and action taken regarding them (when deprived of liberty and reasons for that measure; when told of rights; signs of injury, mental illness, etc; when next of kin/consulate and lawyer contacted and when visited by them; when offered food; when interrogated; when transferred or released, etc.). For various matters (for example, items in the person's possession, the fact of being told of one's rights and of invoking or waiving them), the signature of the detainee should be obtained and, if necessary, the absence of a signature explained. Further, the detainee's lawyer should have access to such a custody record. 41. Further, the existence of an independent mechanism for examining complaints about treatment whilst in police custody is an essential safeguard. 42. Custody by the police is in principle of relatively short duration. Consequently, physical conditions of detention cannot be expected to be as good in police establishments as in other places of detention where persons may be held for lengthy periods. However, certain elementary material requirements should be met. All police cells should be of a reasonable size for the number of persons they are used to accommodate, and have adequate lighting (i.e. sufficient to read by, sleeping periods excluded) and ventilation; preferably, cells should enjoy natural light. Further, cells should be equipped with a means of rest (eg. a fixed chair or bench), and persons obliged to stay overnight in custody should be provided with a clean mattress and blankets. Persons in custody should be allowed to comply with the needs of nature when necessary in clean and decent conditions, and be offered adequate washing facilities. They should be given food at appropriate times, including at least one full meal (i.e. something more substantial than a sandwich) every day.