BY SARAH OWENS
Regular sleeping cycles are just one aspect of healthy brain function that can be negatively affected by a traumatic brain injury (TBI). A new study published online on December 21 in Neurology suggests that a quick return to a normal sleep cycle may help patients regain consciousness faster, follow commands better, and generally improve recovery.
The Science of Sleep
The brain and sleep are closely connected. Through circadian rhythms, the brain is responsible for regulating a 24-hour sleep/wake cycle, during which healthy people are normally asleep for an extended period during the dark nighttime hours and awake for an extended period during the light daytime hours, with no or minimal napping.
After a TBI, sleep/wake periods become fragmented, with short bouts of alternating sleep and wakefulness during the night that often result in daytime sleepiness. Past research shows that when people who've had a TBI return to a normal, 24-hour sleep/wake cycle, they're less likely to have memory loss after being discharged from the hospital, and more likely to have fewer thinking problems during rehabilitation. But the broad association between a return to normal sleep/wake cycles and healthy cognitive function hasn't been closely examined until now.
The Sleep Cycles–Recovery Link
Researchers at the University of Montreal and the University of Quebec in Canada enrolled 30 patients who had sustained a moderate-to-severe TBI and were hospitalized at Hôpital du Sacré-Coeur de Montréal and began recording their sleep-wake cycle an average of three weeks after their injury.
All patients wore a sleep-recording activity monitor that measured when they fell asleep and how long they slept, over a period of 11 days. Using data captured by the monitor, the researchers created three measures that contribute to a normal 24-hour sleep/wake cycle: the daytime activity ratio, which reflects how long patients were awake during the day; the nighttime activity ratio, which reflects how long patients were asleep at night; and the nighttime fragmentation index, which reflects how much patients' nighttime sleep was disrupted and whether patients could stay asleep for long periods without waking up.
Then the researchers measured improvements in the patients' cognitive function, using the Rancho Los Amigos scale of cognitive functioning, which measures TBI recovery. Graded from 1 to 8, the scale measures confusion, attention, awareness of the environment, the ability to respond to stimuli, the ability to follow commands, and the ability to respond appropriately to questions and prompts.
Better Sleep Predicts Better Recovery
The researchers matched the patients' sleep data to their performance on the cognitive tests. They found that patients who returned to a normal sleep/wake cycle more quickly—with longer, more continuous sleep at night and longer periods of wakefulness during the day—were more likely to have a higher score on the cognitive scale.
Additionally, the researchers noticed that improvements in sleep and improvements in cognitive function often happened at roughly the same time. This may mean that similar brain functions underlie sleep regulation and cognitive function, they said.
Overall, the study authors wrote, the results show that a faster return to a normal sleep/wake cycle can speed up recovery. Patients, doctors, and hospitals can employ the following strategies to help speed up the patients' return to a normal sleeping schedule.
- Reduce noise at night. Do what you can to keep nighttime noises low to ensure a continuous, restful sleep.
- Control light levels. A hospital room or bedroom should be sunny and bright during the day, and very dark at night to help patients sleep better.