Guideline #27
Animal Room Light Cycles

1. References:

1.1. Laboratory Animal Medicine , 3rd Edition, 2015, pp. 1566-1567. American College of Laboratory Animal Medicine (ACLAM) Series

1.2. ILAR Guide for the Care and Use of Laboratory Animals , 8th Edition, 2011, pp. 47-49, 81, & 141.

2. Purpose: To provide guidance on light cycle usage and control settings.

3. Policy:

3.1. Light Cycles:

3.1.1. The standard/default diurnal light cycle for most animal species is 12-hr light: 12-hr dark (12L: 12D) with the lights being ON during the daytime (e.g., lights are set to turn ON at 7:00 am and turn OFF at 7:00 pm). The designated light cycle should be documented on the animal room door sheets.

3.1.2. Light cycles with longer photoperiods (e.g., 14L: 10D) may be used with the approval of the IACUC (e.g., rodent breeding colonies, zebrafish colonies, etc.).

3.1.3. Reverse light cycles (i.e., lights are OFF during the daytime and ON during the night) are to be defined and justified in the protocol and approved by the IACUC.

3.1.4. Regardless of the light cycle, at least one daily animal health monitoring check is to be done during the light phase of the light/dark cycle.

3.2. Light Cycle Monitoring:

3.2.1. Room automatic light timer controls should be checked daily to make sure they are displaying the correct time of day and are set to turn the lights ON/OFF at the correct times. These daily checks are documented on the animal room door sheets.

3.2.2. The lights in animal rooms housing animals should be physically checked at least weekly to verify that the automatic light timers are turning the lights ON/OFF at the set times and that the lights are not staying ON/OFF continuously. These weekly physical checks should also be documented on the animal room door sheets.

 

LAST REVIEWED AND ADOPTED BY THE IACUC: March 17, 2022