Report Animal Concerns

All the Bright Moves: Minimizing Light Cycle Disruptions in Animal Housing Rooms

Facilities Husbandry

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Maintaining spaces where environmental variables are minimized to the greatest extent possible plays a critical role in safeguarding animal welfare and ensuring research integrity.

Any changes to light intensity, quality, or duration – disruptions that may seem small and insignificant to us – can have a substantial impact on animal health. Although many species can adapt to a variety of lighting conditions, a consistent photoperiod is necessary for normal reproductive behavior and physiology.

In accordance with the guidelines for facilities, housing, and environmental management set forth by the Guide for the Care & Use of Laboratory Animals, the Unit for Laboratory Animal Medicine (ULAM) uses an established set of standard lighting practices in all animal housing rooms on campus.

As such, most housing rooms employ centrally controlled and monitored light cycles that utilize a 12-hour light / 12-hour dark photoperiod. 

To minimize light cycle disruptions and avoid any unnecessary exposure to light during a room’s dark cycle, please remember the following:

  • When room lights are off, avoid entry whenever possible.
  • If you must enter a room during the dark cycle, use a flashlight or hood light. Red light options may also be available in some areas.
  • If it is absolutely necessary to turn on room lights, use the laminar flow hood or timed lighting override switch (available in select locations). Do NOT open the light timer box.
  • Turn the after-hours light source (i.e., laminar flow hood) off BEFORE exiting the room. Leaving these lights on will cause undue stress to the animals.

Where to Learn More

  • Light cycle timing details can be found on the Room Entry Sign (see picture at right) posted on the door of every animal housing room.
  • Additional information about lighting in animal housing rooms is also covered by ULAM Husbandry Supervisors during facility orientation tours for all new laboratory research personnel.


  • Contact your facility’s ULAM Husbandry Supervisorrequires Level-1 U-M login credentialswith specific questions about lighting or light timers in your animal housing room(s).
  • Promptly report any lighting malfunctions or concerns to your area supervisor so that issues can be addressed in a timely manner.
  • Additional questions about how different environmental variables may impact animal health should be directed to your ULAM Faculty Veterinarian.

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