Question and Answer
A professor of anatomy at the University of Bristol explains why some people wake up in the middle of the night, emphasizing that this phenomenon is not necessarily a sign of a serious disorder, but rather a biological response in the brain. Professor Michelle Sper said that the brain does not fall asleep simply because the body feels exhausted, noting that chronic stress can keep it in a state of alertness even when the body is tired and in urgent need of rest.
She added that the human response to psychological stress evolved over thousands of years to face immediate dangers, such as predators, natural disasters, or conflicts, where survival took priority over sleep. When the brain perceives a threat, the amygdala activates, triggering a “fight or flight” response. The brain releases the hormones adrenaline and cortisol, which increase heart rate, accelerate breathing, and enhance focus and readiness to confront the threat.
She clarified that while this mechanism was essential in the past, it is no longer suited to the nature of modern pressures, which include accumulating emails, work-related stress, financial problems, and constant smartphone notifications. In her remarks, Sper explained that sleep is not merely the absence of wakefulness, but a process that requires the brain to gradually reduce its level of activity. However, chronic stress can keep the brain in a state of hyperarousal, causing it to remain vigilant and preoccupied even when the body feels exhausted.
She pointed out that chronic stress may disrupt the natural rhythm of cortisol, which is typically high in the morning to sharpen the mind and gradually declines as night falls, facilitating the onset of sleep. When this rhythm is disrupted, the body may remain on high alert well into the night. She also noted that light emitted from screens (smartphones and computers) suppresses the secretion of melatonin, the hormone responsible for regulating sleep.
Professor Sper recommended following a consistent sleep routine, minimizing screen use in the evening as much as possible, exercising regularly, and getting exposure to daylight, as all of these practices help the brain recognize that night is a “garden” for rest, not a “playground” for the brain to run around in a state of wakefulness.
Source: The Mirror
