The suprachiasmatic nucleus of the brain, known as the body's "master clock," is responsible for the sleep-wake cycle. This area regulates circadian rhythms—a 24-hour biological cycle that affects sleep, body temperature, appetite, and digestive processes.
Experts emphasize that circadian rhythms vary among individuals: some find it easier to wake up early and go to bed earlier, while others prefer late hours for sleeping and waking. With a consistent schedule of sleep, nutrition, and physical activity, the internal clock adapts, preparing the body for awakening in advance.
Shortly before the usual wake-up time, the level of melatonin—the sleep hormone—drops, body temperature rises, and cortisol levels begin to increase. This phenomenon, known as the "cortisol awakening response," helps a person transition from sleep to wakefulness even before the alarm sounds.
Scientists note that if a person regularly wakes up a little earlier than the alarm and feels rested, it indicates normal functioning of the circadian rhythm. However, if awakening occurs with fatigue, it may be a sign of poor sleep quality or disruption of the schedule.
An irregular sleep schedule can disrupt internal rhythms, causing drowsiness and decreased concentration. In such situations, the body often relies on the alarm clock, which may wake a person during deep sleep, leading to what is known as sleep inertia.
For a more comfortable awakening, scientists recommend maintaining a stable sleep schedule of seven to eight hours, avoiding caffeine and heavy meals before bedtime, limiting screen time in the evening, and ensuring access to natural morning light. They assert that the ability to wake up without an alarm is one of the signs of proper rest and the correct functioning of biological clocks.
