Sunday, August 4, 2013

Babies sleep a lot, don’t they? That seems to be true for more than just humans and mammals! A team of researchers from the Max Planck Institute for Ornithology and the University of Lausanne uncovered fascinating new information about REM sleep.

REM sleep (Rapid Eye Movement Sleep) is the phase of sleep during which we experience our most vivid dreams. During REM sleep, our brain experiences awake-like activity. A distinctive feature of REM sleep is that mammals earlier in their lives experience a greater amount of REM sleep than adults. For newborn humans, 50% of their sleep is REM sleep. Adults spend a quarter or less of their sleeping hours in REM. Birds are the only non-mammalian group of animals that are known to experience REM sleep. However, it was unknown if baby birds experience more REM sleep than adults.

The researchers attempted to solve this mystery, using wild barn owls as their subjects. Using minimally invasive EEGs and movement data loggers, the scientists recorded the sleep behaviour in 66 owlets of varying maturity. Throughout the recordings, which lasted for up to five days, the owlets stayed in their nest and were fed normally by their parents. After the recordings, all the owlets eventually fledged and went on the breed in the following year. So it is clear that this observational study had no adverse effects on the owls.

The results showed that the owlets spent a large amount of time in REM sleep, during which their brains showed awake-like activity. Although their eyes remained closed, the owlets would slowly nod their heads. The researchers also found that the time spent in REM sleep decreased as the owlets matured.

The researchers also investigated the connection between sleep and the expression of a gene responsible for producing dark feather spots. The same gene is also necessary for the production of thyroid and insulin hormones. These in turn are linked to brain development in the owls. One of the researchers mentioned that they had “found that melanic spotting in owls covaries with a variety of behavioral and physiological traits, many of which also have links to sleep, such as immune system function and energy regulation." They discovered that owlets with a higher level of expression of the abovementioned gene experienced less REM sleep than was expected for their age. This suggests that they were experiencing greater brain development than owlets with lower gene expression.

To completely uncover the intricate relationships between REM sleep, feather pigmentation and brain development, additional research must be done. It is hoped that studying the variation of REM sleep with age can provide a clue to the long-standing mystery of REM sleep.

Read all about it: http://bit.ly/145a2m1
Image URL: http://bit.ly/13EPxcA

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