Many people are familiar with this: You suddenly wake up at 3 or 4 a.m. for no apparent reason. The house is quiet, the sky is still dark, and strangely enough, falling back asleep is difficult. Over the years, countless beliefs, spiritual interpretations, and health-related theories have developed around this phenomenon. But what does science actually say about it?
Sleep experts explain that our sleep is divided into cycles that repeat every 90 to 120 minutes throughout the night. At the beginning of the night, we spend more time in deep sleep. As morning approaches, the body naturally transitions into lighter sleep phases. Between 3 and 4 a.m., many people are in one of these lighter phases, which makes them more easily awakened even by minor disturbances such as noise, temperature changes, or internal bodily signals.
Stress and anxiety are among the most common reasons for waking up in the early morning hours. During quiet moments, the mind becomes more active, and unresolved worries can surface. Even if someone falls asleep easily, emotional tension can cause the brain to be partially awake in the early morning. This is why people suffering from chronic stress often report waking up at the same time every night.
Another important factor is blood sugar regulation. The body also regulates glucose levels at night. If blood sugar drops too low, stress hormones such as cortisol and adrenaline are released to stabilize it. These hormones can also increase alertness and thus lead to sudden awakenings.
