It is thought that the amount of sleep received every night affects the brain’s memory and retention, with less sleep resulting in lower retention rates and vice versa.
Studies suggest that healthy sleep facilitates neural plasticity which is thought to underlie the consolidation of newly acquired and initially unstable memories. As teenagers, such a topic had so much appeal to us given our academically competitive environment at school and made us curious about the effect of lack of sleep on cognitive function. It is highly likely that more than half of the attending students don’t get anywhere close to the suggested 9 hours of sleep on a daily basis. Even older students, such as seniors like ourselves, receive even less sleep than the amount required for our bodies.
The ending result of this lack of sleep is ultimately reflected in negative impact on our work effort and memory retention. Description of StudyPrimary insomnia is a prevalent health problem affecting approximately 5% of the adult population. In addition, patients with primary insomnia frequently report difficulties falling asleep, staying asleep, or maintaining non-restorative sleep. In addition to these difficulties experienced at night people also report issues during the day, such as memory dysfunction. However, previous research that examined memory consolidation across periods of daytime wakefulness largely failed to provide objective evidence for subjective memory complaints.
Additional relevant studies on memory in patients with sleep disorders have been addressed in the 2006 National Academy of Sciences Report, which states that “awareness should be increased about the importance of sleep to health, performance, and learning.” Studies suggest that overnight improvement in a procedural motor task might be impaired in patients with primary insomnia compared to good sleeper controls. Other studies examined declarative memory consolidation during sleep and found that this type of memory consolidation might be attenuated in patients with primary insomnia compared to good sleeper controls. However, both studies only assessed overnight memory consolidation in between the learning and recall periods, and were limited by the lack of a wake comparison condition needed to demonstrate sleep-specific effects. These studies were designed to investigate memory consolidation across equal periods of night-time sleep and daytime wakefulness in patients with primary insomnia (PI) and measured with good sleeper controls (GSC).
In the Department of Psychiatry and Psychotherapy at the University Medical Center in Freiburg, Germany, Dr. Christoph Nissen tests healthy subjects. He tested to see if retention intervals containing sleep would foster the consolidation of procedural and declarative memories when compared to retention intervals containing only wakefulness. This effect of sleep would be impaired in patients with primary insomnia. He and his team worked to find if patients with PI would show deficits in sleep-related memory consolidation compared to GSC.
Conducted at the Sleep Laboratory at the Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center, clinical experiments conformed to the principles outlined by the Declaration of Helsinki. The procedure used to test insomnia and sleep versus memory was approved by the local ethic committee prior to the onset of the study. Tested on 52 healthy patients, 33 with clinically assessed and reviewed primary insomnia, a 4-group parallel design was used to investigate the effects of 12 hours of night-time monitored sleep versus 12 hours of daytime wakefulness on procedural and declarative memory consolidation. Memory was tracked using procedural memory and declarative memory, and general cognitive performance were assessed either at 20:00-08:00 hours (“sleep condition”) or at 08:00-20:00 hours (“wake condition”). Subjects were then tested with equal retention intervals of 12 hours between the learning and recall sessions in both conditions. Participants in the “sleep condition” slept in the sleep laboratory with polysomnographic monitoring from 22:30-06:30 hours.
While in free periods of wakefulness, participants were instructed to continue their normal routines, including their normal sleep as well as their typical amount of mental and physical activity to keep levels of interference comparable.In order to test these levels of memory retention, participants were given two different assessments. In the visual assessment, patients were asked to work as quickly and accurately as possible. The “mirror tracing task” required subjects to trace different line-drawn stimuli using a stylus.
The results were then measured with a light sensor to determine the amount of time taken to complete the task and the number of errors or how many times the stylus strayed from the line. In the visual and verbal test, subjects were required to memorize a line-drawn path on a visual map and the information about the construction of a building provided in the form or text. Patients would then have to recall what was measured without the use of the original learning material. This measure of declarative memory was calculated using the percentage of retrieved items in the recall session (retention rate, %). Additionally, sleep recordings were logged from 22:30 to 6:30 hours and scored by the sleep laboratories in determining which stage of sleep the patient was in and how long they were in that stage of sleep.
Some factors of bias included in this experiment include varying night time ritual, amount of stress which affects the density and length of sleep (i.e. waking up in the middle of the night, using the bathroom), and