After trauma, the nervous system can shift into a persistent state of heightened alertness that disrupts a person’s sense of safety, emotional balance, and ability to rest. The amygdala—the brain’s alarm system—often becomes more sensitive and reactive, making it easier for neutral situations to feel threatening. This increased vigilance can lead a person to interpret ordinary cues, such as riding in a car or hearing an unexpected sound, as signals of danger.

At the same time, the prefrontal cortex, which supports reasoning, decision-making, and emotional regulation, may become less active during stress. This reduced engagement can make it harder to calm intense emotions or evaluate situations logically. As a result, individuals may find themselves overwhelmed by fear, irritability, or anxiety even when they recognize, on some level, that they are safe. This imbalance between heightened threat perception and decreased regulation creates significant challenges in achieving a sense of internal stability.

Physiologically, trauma can keep the sympathetic nervous system—the “fight, flight, or freeze” response—chronically activated. Elevated heart rate, muscle tension, and a sense of being on guard can persist long after the event itself. When the body remains in this hyperaroused state, sleep becomes difficult: the mind races, the body feels restless, and falling or staying asleep can feel unsafe. Nightmares, intrusive thoughts, and repeated nighttime awakenings further disrupt the sleep cycle and reinforce the nervous system’s heightened state.

Meanwhile, the parasympathetic system, responsible for rest, digestion, and restoration, often struggles to counterbalance this ongoing activation. Because restorative sleep requires the ability to shift into a calm physiological state, trauma survivors may find it difficult to wind down at bedtime, relax enough to fall asleep, or return to sleep after waking. Quiet and darkness can also act as triggers, as reduced stimulation may give space for intrusive memories or feelings to surface, creating anxiety around bedtime itself.

These changes often create a self-reinforcing cycle: hyperarousal disrupts sleep, and poor sleep intensifies stress, irritability, and emotional sensitivity. Over time, this cycle can lead to cognitive fatigue, weakened immune function, and increased vulnerability to mood disturbances. Breaking this pattern requires addressing both the body’s stress response and the emotional impact of trauma.

Restoring restorative sleep after trauma involves helping the nervous system relearn how to shift into a state of safety and calm. Some specific areas of concern to address may include insomnia, nightmares, or hypervigilance.