Why You’re Waking Up at 4am

If you’ve been under pressure lately, your early wake-ups could be tied to stress hormones doing their job—just a little too early. Cortisol, which helps you feel awake and alert, naturally starts rising in the early morning hours to prepare you for the day. But when your body is on high alert due to chronic stress or anxiety, those cortisol levels can spike prematurely and wake you up before you’re ready. This can leave you feeling wired at the worst possible time, even if you’re still physically exhausted. You may notice your thoughts racing the moment your eyes open, especially if you’ve been mentally overloaded or emotionally drained during the day.

Not eating enough in the evening or having your last meal too early can lead to drops in blood sugar while you sleep. When your glucose levels fall too low, your body releases adrenaline and cortisol to bring them back up—and that process can jolt you out of deep sleep. If you often wake up with a slight sense of restlessness, a rapid heartbeat, or even mild anxiety around 4am, it could be a subtle sign of a nighttime glucose dip. This is especially common in people who eat dinner several hours before bed or follow a low-carb or intermittent fasting routine.

Your sleep-wake cycle is closely tied to your hormonal system, which fluctuates throughout your life—and even throughout the month. As melatonin production slows toward morning and cortisol ramps up, your body naturally transitions toward wakefulness. But for some people, especially women experiencing hormonal shifts during perimenopause or menopause, these transitions become more pronounced. Hot flashes, mood changes, and disrupted sleep patterns are all part of the package, and they often show up as early-morning awakenings. Even outside of menopause, things like thyroid imbalances or irregular menstrual cycles can throw off your natural sleep rhythm.

Your sleep happens in cycles, and most people go through several in one night. Each cycle includes periods of lighter and deeper sleep, along with REM stages that increase toward morning. Waking at 4am may simply mean you’ve completed a sleep cycle and entered a lighter stage—one where it’s easier to be disturbed. If your room is slightly too warm, if there’s a shift in light, or if any noise occurs, that lighter stage can turn into full wakefulness. Once awake, it can be tough to slip back into sleep, especially if your brain starts to engage or you start checking the time.

In the last few hours of the night, your body spends more time in REM sleep—a lighter, more active sleep stage associated with dreaming. Unfortunately, it’s also the most sensitive to disruption. Anything from an unexpected noise to a cold draft in the room can wake you during REM, and the timing often lands right around 4am. Even small shifts in temperature, subtle background lights, or a buzzing device on the nightstand can be enough to nudge you awake. Once your REM cycle is interrupted, it’s harder to fall back into deep sleep, and you may end up tossing and turning until morning.

Mental health conditions like depression can significantly impact sleep—sometimes showing up as insomnia, other times causing early morning awakenings. This pattern is especially common with seasonal or situational depression, where mood changes align with certain times of the year or life stressors. Waking up too early can be a symptom of an underlying emotional imbalance, even if you’re not consciously aware of feeling down. If your early wake-ups are paired with feelings of fatigue, sadness, irritability, or changes in appetite, it might be worth checking in with a professional to explore what’s going on beneath the surface.

Circadian rhythm disruptions can make it hard for your body to stay asleep until morning. Whether it’s due to late-night scrolling, recent travel across time zones, shift work, or even inconsistent sleep habits, any change to your routine can shift your internal clock. This can result in your body believing 4am is an appropriate wake time—even when you know it’s not. Over time, your system can become trained to wake up too early, reinforcing the pattern night after night. Resetting your circadian rhythm requires consistency: going to bed and waking at the same time each day, reducing screen time before bed, and avoiding bright lights late in the evening.