Cannot Sleep at Night? Could It Be the Season? When Sunlight Fades, Sleep Fades Too

What Donguibogam describes as the yin and yang changes of heaven and earth and the harmony of yin and yang inside the body can be clearly explained in modern medicine through the circadian rhythm and the role of the hormone melatonin. Inside our brains lies a tiny region called the suprachiasmatic nucleus. This suprachiasmatic nucleus acts as a master clock regulating all biological rhythms in our body. This clock perceives time primarily through light, especially sunlight. When you open your eyes in the morning, the light entering through your eyes tells the suprachiasmatic nucleus that it is daytime, stimulating the secretion of hormones for daytime activity. When the sun sets and darkness falls, it sends a signal that it is night and time to prepare for sleep, prompting the pineal gland to secrete the sleep-inducing hormone melatonin. The problem arises in seasons like autumn or winter, when the amount of sunlight decreases drastically. When daytime shortens and we do not get enough sunlight, our brains face difficulty clearly distinguishing day from night. If the signals from the suprachiasmatic nucleus weaken due to insufficient light, the switch for melatonin secretion stops functioning properly. During the day, the secretion of neurotransmitters that induce arousal, such as serotonin or dopamine, decreases, which may leave you lethargic, sleepy, or low in mood. At night, melatonin is not secreted at the right time, or its secretion rhythm breaks down, preventing you from falling into deep sleep. When this phenomenon becomes severe, it can be diagnosed as seasonal affective disorder, which mainly appears in autumn and winter and is also referred to as winter depression. Seasonal affective disorder does not merely lower mood; it also accompanies changes in sleep patterns, increased appetite, weight gain, and fatigue, and can trigger insomnia. Because the body lacks sun exposure, vitamin D production also drops, which again affects serotonin synthesis and can adversely impact mood and sleep. Ultimately, seasonal insomnia can be understood as more than just a phenomenon of being unable to sleep. It is a complex signal sent when the delicate hormone and nervous systems fail to adjust to the great shifts of nature. Therefore, rather than blaming your body on sleepless nights, it is important to offer it care so that it can adapt better to nature.