Scientists Investigate Sleep With Mutant Mice

The carrier of one of the mutations was the Sonya mouse, which required a third more sleep than the rest of the individuals. The second mutant was named Sleepless - he had a significantly shorter REM sleep stage.

Photo: Martha Sexton /

We spend about a third of our lives in sleep. It is necessary for the normal functioning of the body - however, despite the fact that it is so important, scientists have not yet figured out its physiology. Until now, it remains a mystery how the process of falling asleep and waking up is regulated, there is a hypothesis that there is a certain substance that is concentrated when a person or another creature is awake, and is released when he / she falls asleep. To understand these processes, experts, as usual, turned to studies in mice.

Read More: Lack and Excess Sleep Harm Health

It is known that lack of sleep can lead to serious health problems. Those who sleep little are more likely to develop diabetes and obesity. However, a lot of sleep is also bad - such conclusions were made by researchers from the University of Columbia (Columbia University).

The scientific work was done by Joseph Takahashi of the University of Texas and Masashi Yanagisawa of the University of Tsukuba. They studied genetic mutations that caused the mice to sleep differently. At the same time, as Takahashi explained, he and his colleague provoked random mutations in more than 8 thousand mice - in order not to examine a much larger number of animals in search of something interesting at the genetic level, they decided to create this interesting one on their own. All mutated mice were subjected to electroencephalography.

Of the 8,000 mutations, only two have attracted the attention of scientists. The carrier of one of them was the Sonya mouse, which required a third more sleep than the rest of the individuals. The second mutant was named Sleepless - he had a significantly shorter REM sleep stage. Sonya had a damaged gene for salt-induced kinase-3. In order to understand why he sleeps so much, Joseph Takahashi and Masashi Yanagisawa studied him comprehensively, for example, they checked whether there was a disturbance in his circadian rhythms, as well as whether the mouse responded normally to various stimuli (new cell, caffeine). Except for a mutation in the genes, both Sonya and the Sleepless, who was tested in the same way, were all right. The researchers concluded that while the physiological reasons for the first mouse's increased need for sleep are unclear, it is possible that mutation is the determining factor. As for the Sleepless, everything turned out to be somewhat easier with him, his mutation increased the conductance of the sodium channel, which is responsible for the excitability of neurons.

The authors of the scientific work hope that further screenings will identify additional mice whose gene changes will affect their sleep. Perhaps these animals will contribute to the disclosure of the secrets associated with this state. Masashi Yanagisawa added that "this is just the beginning."

Source: Mouse mutants with sleep defects may shed light on the mysteries of sleep

The first unbiased genetic screen for sleep defects in mice has yielded two interesting mutants, Sleepy, which sleeps excessively, and Dreamless, which lacks rapid eye movement (REM) sleep. The findings are the first step towards discovering the biochemistry that controls the switch from wakefulness to sleep, the researchers say.

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