Melatonin Helps with Sleep and Memory Disorders

2025-01-14

Sleep is a major life event, as one third of a person's life is spent in sleep. Good sleep is important for restoring energy and promoting health. However, statistics from the China Sleep Research Society show that in 2021, more than 300 million Chinese people will suffer from sleep disorders. In recent years, melatonin-related products are young people, especially white-collar workers respected as “sleep medicine”, in many e-commerce activities in the sales ranking, “melatonin” product sales also ranked in the forefront of health care category. So, how exactly does melatonin solve the problem of sleep and memory disorders?

Increasing the duration of rapid eye movement sleep

Melatonin is a humoral regulator released by the pineal gland and plays an important role in sleep mediation. Research has revealed the mechanism of action of melatonin in regulating non-REM sleep by affecting the PVT, and found that melatonin can inhibit the activity of PVT neurons and increase the duration of non-REM sleep, which is conducive to falling asleep. PVT can be understood as a switch in the brain that controls wakefulness and sleep, and there are many locks on this switch, which are melatonin type 1 and type 2 receptors, and melatonin is the key to these locks. By binding to its receptors, melatonin turns off the PVT “switch,” which leads to a significant increase in the duration of non-REM sleep and helps people sleep more deeply. Conversely, if the binding of melatonin to its receptors in the PVT is blocked, the duration of non-REM sleep decreases and the time spent awake becomes longer.

In addition, it has been shown that melatonin receptor expression is rhythmic, with the number of melatonin receptors changing with the change of night and day. In short, when night comes, melatonin will begin to be secreted and act on PVT neurons, and the brain will be more likely to enter a restful state. This is a reminder to people with sleep disorders that when using melatonin to assist in the treatment of insomnia, it should not be used as a simple sleeping pill, and that maintaining a regular routine is vital to maintaining a good night's sleep.

Promote neuronal retraction to enhance memory

The homeostasis theory of sleep neurons suggests that new information is constantly being fed into the brain during awakening, and in order to adapt to the need for information transfer, neuronal volume is increasing, which facilitates the establishment of synaptic connections between neurons. However, neuronal volume does not increase indefinitely. During sleep, as the function of receiving external stimuli is weakened, neurons will undergo morphological and structural retraction to better cope with the task of waking up the next day. Studies have shown that melatonin secretion levels increase when arousal transitions to sleep, and melatonin reaches the PVT via the cerebrospinal fluid pathway, utilizing the lower expression of melatonin type 1 and type 2 receptors within the PVT. If melatonin type 3 receptors are inhibited during sleep, it will significantly cause impaired retraction of dendritic spine morphology in memory neurons.

It can be speculated that impairment of melatonin secretion and its receptor signaling may be a potential pathological factor in the development of sleep and memory disorders in some major neurological diseases. In the future, the development of co-application of type 3 receptor agonists is expected to further improve the quality of sleep and enhance memory capacity.