Credit: Vera Kratochvil/public domain
Shifting Sleep Cycle affects Immune response, sleep quality. Ilia Karatsoreos, an assistant professor in WSU’s Department of Integrative Physiology and Neuroscience, shifted mice from their usual cycle of sleeping and waking and saw that, while they got enough sleep, it was of poorer quality. The animals also had a disrupted immune response, leaving them more open to illness.
Most sleep research focuses on the effects of sleep deprivation or the overall amount of sleep an animal needs. This is generally referred to as sleep’s homeostatic process, which is driven by sleepiness or “sleep pressure.”
“…disruption of the circadian clock is nearly ubiquitous in our modern society” due to nighttime lighting, shift work, jet lag and even the blue-tinged light emitted by cell phones and tablets.
Typically, sleep researchers have a hard time studying sleep deprivation and the circadian cycle separately, as a change in one usually affects the other. However, Karatsoreos and his colleagues saw their model did not affect an animal’s total sleep, giving them a unique look into the effects on the timing of the sleeping-waking cycle.
METHOD: They used mice whose body clocks run at about 24 hours – much like our own – and housed them in a shorter 20-hour day. This forced their biological clocks out of sync with the light-dark cycle. After 4 weeks, the researchers injected the mice with lipopolysaccharide, a molecule found in bacteria that can make an animal sick without being contagious.
RESULTS: The disrupted animals had blunted immune responses in some cases or an overactive response in others, suggesting the altered circadian cycle made them potentially less able to fight illness and more likely to get sick.
To his surprise, the mice on the 20-hour cycle were getting the same amount of sleep as they did on the 24-hour cycle. But the sleep wasn’t as good. The mice woke more often and the pattern of electrical activity in their brains related to restorative sleep was greatly reduced. http://www.eurekalert.org/pub_releases/2015-09/wsu-tto083115.php
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