Researchers Identify the Beneficial Role of Sleep

Scientists studied the zebrafish model to find that sleep repairs the damage (done to the DNA during the waking hours) by increasing Chromosome Dynamics.  

You might have observed that sleep disturbances have a drastic impact on your brain performance. Similarly, the lack of sleep for longer duration is linked with several brain disorders and aging. Historically, all the organisms with a nervous system had a regular pattern of sleep in their lifestyles. Despite all these observations, the reason why animals sleep is still unknown to humanity. Having said that, the researchers at Bar-Ilan University may have found the connection by making use of the 3D time-lapse imaging techniques. They defined sleep in a single chromosome resolution of a live zebrafish and revealed that single neurons cannot perform nuclear maintenance without sleeping.

Sleep and DNA Damage

There are a number of processes that lead to DNA damage. Some common ones among them are Oxidative Stress, Radiation, and Neuronal Activity. Each cell is equipped with an individual DNA repair system, which is responsible for correcting this damage.

The researching team showed that DNA damage can reach detrimental levels because it accumulates continuously (happens due to low chromosome dynamics) while we are awake. They found that sleep normalizes the levels of DNA damage in each of these neurons by increasing chromosome dynamics. The efficiency of this process is not up to the mark during wakefulness. It requires an offline period with reduced input to the brain to provide the best results. Lior Appelbaum, a Professor of Life Sciences at Bar-Ilan University who led the research, explained that procedure in the following words:

“It’s like potholes in the road. Roads accumulate wear and tear, especially during daytime rush hours, and it is most convenient and efficient to fix them at night, when there is light traffic.”

Appelbaum considers this accumulation of DNA damage the price of wakefulness. Alongside his colleagues, he hypothesized that sleep is responsible for consolidating this damage and ensuring nuclear maintenance within neurons.

The Zebrafish Model

Out of all the animals, the characteristics of the zebrafish model came to their aid as the brain of this organism is quite similar to humans. They are an ideal candidate for studying single cell within a live animal under physiological conditions due to their absolute transparency. Researchers used a high-resolution microscope to track the movement of nuclear proteins and DNA within the cell of the zebrafish, while it was awake and asleep. The finding that shocked the researchers the most was that chromosomes are more active when the body is in rest mode. This increment in activity assists the repairing of the DNA damage to keep it to optimal levels.

Restorative Function of Sleep

In light of these results, the researching team established chromosome dynamics as a potential marker for defining single sleeping cells. Similarly, they were able to determine a conclusion that nuclear maintenance is a restorative function of sleep. Appelbaum accepted that the link they found is quite casual but it is good enough to give them the result they were looking for. He said,

“We’ve found a causal link between sleep, chromosome dynamics, neuronal activity, and DNA damage and repair with direct physiological relevance to the entire organism. Sleep gives an opportunity to reduce DNA damage accumulated in the brain during wakefulness.”

He mentioned that all the organisms, ranging from zebrafish to humans, have to go offline in order to perform efficient DNA maintenance inside their neurons. He concluded the matter by saying,

“Despite the risk of reduced awareness to the environment, animals — ranging from jellyfish to zebrafish to humans — have to sleep to allow their neurons to perform efficient DNA maintenance, and this is possibly the reason why sleep has evolved and is so conserved in the animal kingdom.”