Approximately 30% of patients with significant head trauma will complain of a significant disruption of sleep. In more significant brain injuries, doctors are often concerned with increased sleeping and altered levels of consciousness. This blog is focused on mild TBI and its interruption of normal sleep patterns- essentially, the lack of a good night’s sleep after head trauma.
As noted above, insomnia is common after head injury- up to 40% of patients suffering from a concussion have difficulty sleeping. This is true in many patients who have never before had difficulty sleeping.
Several questions immediately come up in research related to the brain and insomnia.
The human brain is programmed with circadian rhythms, a 24-hour biological time clock that regulates daily function. The circadian rhythms are influenced by hormonal levels in the blood as well as structural elements of the brain tracking time. The human being, and most animals, have evolved in such a manner that approximate time of day is important (especially daylight and night).
Traumatic brain injury (TBI) has been demonstrated to directly disturb this well-tuned physiological function. People impacted with TBI have difficulty falling asleep and staying asleep. Sleep is critical for returning to normal neurological function after brain injury. Even though sleep is still poorly understood, it is critical in allowing the brain to return to a normal chemical state after a busy day. The amount of energy and metabolic resources necessary to maintain consciousness cannot be underestimated. The heart, the kidneys, and liver don’t need to rest- the brain must rest to function.
Now, an injured brain needs additional recovery time so a good night’s sleep is important to rapid recovery. Head injury victims usually don’t get this privilege.
We all know that lack of sleep can ruin the following day. Everyone intuitively knows that not sleeping clouds judgement and slows work performance. A person can catch up with one bad night, but a chronic condition is a vicious cycle. We don’t even need the medical literature to draw this obvious conclusion. And it’s not just circadian rhythms, it can be simple head, neck, and back pain after whiplash. Pain disrupts sleep. Often, adding pain medication and sleep medication just leads to a diminished level of awareness, but not a cure.
Insomnia can be treated in many ways after a head injury, but this blog is not going to explore treatment. Let’s bring the discussion back to the eyes. The eyes are also metabolically active during the day when we process light information. The cells in the retina need replenishment after a busy day of seeing. This replenishment can be measured by examining cellular activity at night, especially the rods and cones (the photoreceptors).
But it’s more than just rods and cones, it is the surface of the eye. The eyes dry out after not sleeping, the eyelid muscles go into spasm (twitching). Thus, the direct mechanical function of the eyeballs is diminished. Again, people don’t need scientific studies to reach this obvious conclusion. Every individual has experienced the foreign body sensation,
the redness, and fatigability of the eyes after not sleeping. Even simple focusing becomes impossible.
The eye and brain are again tied together, they both need rest. TBI disrupts this normal recovery process. If the eyes aren’t working well, the brain can’t function properly. Over-the-counter eye drops may help temporarily to get the red out, but such medications don’t work in the long run- insomnia works against the entire process. The eyes and brain need their sleep.
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Steven H. Rauchman, M.D. is an eye physician and surgeon who has been in private practice for 30 years. He has served as a Traumatic Brain Injury (TBI) medical/legal expert for the last 6 years specializing in the area of personal injury and related traumatic brain injuries.