Insomnia and Circadian Rhythm Disruption After Brain Injury

For many survivors, it reflects a disrupted internal clock.

Insomnia is the most frequently reported sleep complaint after traumatic brain injury. It can show up as trouble falling asleep, trouble staying asleep, or waking far earlier than intended. In many survivors, this insomnia is tied to a second, related problem: a circadian rhythm that no longer runs on the same schedule as the rest of the household.

Why Insomnia Is So Common After TBI

A meta-analysis of 21 studies published in Sleep Medicine found that half of all people with traumatic brain injury report some form of sleep disturbance, and 25 to 29 percent go on to receive a diagnosed sleep disorder (Mathias & Alvaro, 2012). Insomnia accounts for a large share of that group.

Mathias JL, Alvaro PK. Prevalence of sleep disturbances, disorders, and problems following traumatic brain injury. Sleep Medicine. 2012;13(7):898-905.

Part of what makes TBI-related insomnia different from ordinary sleeplessness is where the disruption originates. The brain regions involved in regulating sleep and wakefulness, including the hypothalamus and brainstem, are also among the regions most vulnerable to injury from acceleration, deceleration, and impact forces. When these regions are affected, the brain's ability to properly initiate and maintain sleep is affected along with them.

The Circadian Rhythm Connection

The body's circadian rhythm, its roughly 24-hour internal clock, is governed largely by the hormone melatonin, which is released by the pineal gland in response to darkness and suppressed by light. This clock tells the body when to feel alert and when to feel ready for sleep.

A study measuring melatonin directly in TBI patients found that, compared to healthy individuals, those with TBI produced 42 percent less melatonin overnight, and the timing of their melatonin release was delayed by approximately 1.5 hours (Grima et al., 2016). This is a measurable, physical shift in the body's internal timing system, not a matter of habit or discipline.

Grima NA, Ponsford JL, St Hilaire MA, Mansfield D, Rajaratnam SM. Circadian melatonin rhythm following traumatic brain injury. Neurorehabilitation and Neural Repair. 2016;30(10):972-977.

This delayed and reduced melatonin signal helps explain a pattern many caregivers describe: a loved one who feels most alert late at night and struggles to wake or function in the morning. The body's clock has genuinely shifted later, even though the household's schedule has not.

Because circadian rhythm sleep-wake disorders require different treatment than general insomnia, correctly identifying which one is present matters. A study of people with chronic insomnia symptoms following mild TBI found that 26 percent had a diagnosable circadian rhythm sleep-wake disorder, most commonly delayed sleep-wake phase disorder, in which the entire sleep period shifts later than a person intends (Zalai et al., 2020). The study's authors noted that insomnia symptoms are a major predictor of poor recovery after concussion, and that identifying a circadian component specifically can change how it's treated.

Zalai D, Girard TA, Cusimano MD, Shapiro CM. Circadian rhythm in the assessment of postconcussion insomnia: a cross-sectional observational study. CMAJ Open. 2020;8(1):E142-E148.

What This Looks Like in Daily Life

For families, this often shows up as a mismatch rather than a single obvious symptom. A survivor may report feeling wide awake at 1am, or may be difficult to rouse in the morning despite adequate hours in bed. Naps during the day can further shift the schedule later, making the pattern harder to correct without intervention. None of this reflects a lack of effort on the survivor's part. It reflects a shifted internal clock working exactly as the injury left it.

What You Can Do

For the survivor

• Ask a doctor about a formal circadian rhythm assessment, not just a general insomnia evaluation, since the two require different treatment approaches
• Track actual sleep and wake times for two weeks before the appointment; this data is useful for distinguishing insomnia from a circadian shift
• Discuss timed light exposure or melatonin timing (not just melatonin dosage) with a sleep specialist, since timing is often the more important variable
• Keep a consistent wake time even on difficult mornings, since wake time anchors the circadian clock more effectively than bedtime does

For the caregiver

• Recognize that a shifted sleep schedule is a physiological finding, not a behavioral choice, when deciding how to respond to it
• Loop in your own doctor if your sleep is being disrupted by a mismatched household schedule; caregiver sleep loss deserves its own attention
• Bring a two-week sleep log to appointments if possible; specific timing data helps a specialist far more than a general description

Peer-Reviewed Citations

1. Mathias JL, Alvaro PK. Prevalence of sleep disturbances, disorders, and problems following traumatic brain injury: a meta-analysis. Sleep Medicine. 2012;13(7):898-905.
2. Grima NA, Ponsford JL, St Hilaire MA, Mansfield D, Rajaratnam SM. Circadian melatonin rhythm following traumatic brain injury. Neurorehabilitation and Neural Repair. 2016;30(10):972-977.
3. Zalai D, Girard TA, Cusimano MD, Shapiro CM. Circadian rhythm in the assessment of postconcussion insomnia: a cross-sectional observational study. CMAJ Open. 2020;8(1):E142-E148.

Robbins Nest Alliance is a 501(c)(3) nonprofit providing free brain injury education for caregivers, veterans, and families. All content is peer-reviewed and cited. This article is for educational purposes only and is not a substitute for medical advice. Always work with your qualified care team.