We eat in a hurry, we want to do as many things at once and, of course, want to sleep as little as possible. A life so hectic leads, however, to sleep disturbances. How many of us know what effect fragmented sleep may have on us on us on the long run? The last study by researchers at Stanford University has shown that interrupted sleep affects the capacity of animals to recall familiar images. The study was conducted in mice, and the discovery published in the journal Proceedings of the National Academy of Science could explain the memory problems of Alzheimer’s and sleep apnea patients.
The human brain uses deep sleep to assess what happened during the day and decide what to keep and what not, say British experts in sleep problems. The study concerned the fragmented sleep with the same duration as normal sleep and with the same intensity. The researchers used a technique called optogenetics (a developing field that combines optical and genetic analysis techniques to test the neural circuitry of mammals and other animals within a few seconds, in order to understand how the brain works) in which some cells are genetically modified to be sensitive to light. Researchers have proposed to study a certain type of brain cells that play an important role in the transition from sleep to wake.
They sent beams of light directly into the brains of mice that slept, allowing interruption of their sleep without changing its total length, quality or structure. Thereafter, mice were put in a box with two objects. One of them was familiar, and the other one was new to them. Normally, mice would have spent more time studying the new object, which happened whit mice whose sleep was not interrupted. Those with fragmented sleep were equally interested in both objects, indicating that memory has been affected.
“Continuity of sleep is one of the most important elements in various pathological diseases which affect memory, including Alzheimer’s disease”, researchers said. The alcoholics and sleep apnea patients (a condition characterized by cessation of breathing repeatedly during sleep) have a bad sleep at night. “Unfortunately, we found that no matter how short is the sleep, even a small disruption leads to worsening of the memory”, the researchers added. It was not demonstrated that sleep disorders could, however, cause these diseases.
“During the days we accumulate memories. At some point we need to sort them, and some of them need to be saved in a permanent place. This process occurs during deep sleep, so anything that affects sleep will have a direct effect on memory”, said Dr Neil Stanley, a member of the Sleep Research Society of Great Britain. He also added that nocturnal apnea sufferers have problems with “saving” these memories, and those suffering from Alzheimer’s often have trouble sleeping. “We do not know whether brain degeneration is responsible for bad sleep or vice versa”, added the Briton researcher.