The human body is designed to live during the day and sleep at night, because we are diurnal animals. This rhythm is spread over 24 hours, and can vary slightly from one individual to another: this is the circadian clock.
The role of sleep and the circadian cycle directly influences memory and brain function, as shown in a study done on hamsters. Biologists have shown that an optimally functioning circadian cycle is essential for hamsters to remember what they have learned. Animals with disrupted clocks had difficulty remembering their environment, unlike those with good circadian cycles.
The change in learning appears to be highly dependent on GABA, γ-aminobutyric acid, a widespread chemical messenger in the brain that runs nearly 40% of synapses and that the circadian clock uses to control the daily sleep-wake cycle.
This study shows that the internal clock must be functioning in the best conditions to learn and retain what has been learned.
In short, your circadian clock controls the daily cycle of sleep and wakefulness by alternating inhibition and regulation of the release of certain neurotransmitters. The hippocampus needs to be stimulated so that things learned can be acquired and reused in the future. When this clock is not functioning properly, too much GABA is released which can lead to short-term memory problems and an inability to assimilate and retain new information.
If you stay up very late, deprive yourself of enough sleep, or eat at late hours when your body should be sleeping, you are sending mixed signals to your body. To counteract this, the body will produce "sleep chemicals" during times when you should be awake and alert, and the opposite when you need rest.
Based on the observations of the above mentioned study, it is evident that a link between a poor circadian cycle, poor sleep quality and quantity, and memory problems, especially in the aging population, is to be deplored.
But no matter what age you are, the best way to keep your clock functioning optimally is to make sure you get the amount of sleep you need, and most importantly, that it's good.
Good sleep is an essential requirement for good health, no matter what age group you are in. Even if everything else is done in a healthy and optimal way (food, sports, stress management, etc.), if you don't give yourself enough quality sleep, you simply cannot be healthy.
The circadian rhythm regulates the activity of your entire body: brain, lungs, heart, liver and skeletal muscles. It keeps all organs and systems running smoothly. Memory is not the only thing that is affected by a bad circadian cycle. Indeed, a faulty clock can have adverse effects on overall health, weight, stress and even be the cause of cancers.