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Fragmented Sleep

Written by Jocelyn Zakri MPH, RRT, RPSGT, RST


Fragmented sleep involves many brief arousals throughout the night.

What is Fragmented Sleep?

Do you fall asleep quickly, but wake up repeatedly throughout the night? You may have fragmented sleep, along with the daytime sleepiness it causes.

Sleep fragmentation is defined as many brief arousals throughout the night. These are not the naturally occurring microarosuals that most people experience every night during sleep. Microarousals are normal and occur in humans and other mammals during transitions between sleep cycles, and generally don’t cause daytime fatigue.

Rather, fragmented sleep involves awakenings that the sleeper recalls later. People with this type of fractured sleep struggle to get back to sleep after these awakenings, which decreases their total time spent asleep and leads to daytime fatigue.

Those who experience sleep fragmentation may have a condition called sleep-maintenance insomnia; that is. they can fall asleep at bedtime, but can’t sleep through the night. By contrast, sleep onset insomnia occurs when people struggle to fall asleep at bedtime.

Some people experience unfragmented, or consolidated, sleep in two periods during the night, with a longer awakening in between. This is not considered fragmented sleep. Rather, this is considered biphasic sleep, and it is fairly common.

Why Does Fragmented Sleep Matter?

Unrefreshing, unsatisfying sleep is more than an annoyance. This condition has serious health consequences, including weight gain, mood problems, and excessive daytime sleepiness.

In a recent study by Johns Hopkins University School of Medicine, just one night of fragmented sleep cut happiness levels by nearly one-third.

How Common is Fragmented Sleep?

Fragmented sleep isn’t an official sleep disorder. Instead, it’s considered a symptom of other sleep disorders like obstructive sleep apnea and narcolepsy. While sleep fragmentation is common, its exact prevalence is unknown.

Diagnosis and Treatment

Sleep medicine physicians use the Sleep Fragmentation Index (SFI) to measure the amount of sleep disruption experienced by people with fragmented sleep. The SFI is determined by dividing the total number of awakenings and sleep stage shifts by total sleep time.

Actigraphy, or the measurement of sleep-wake stages using a small wrist-worn device, can help track awakenings to detect fragmented sleep. And a doctor may recommend polysomnography, an overnight sleep study, to evaluate sleep patterns and determine whether a sleep disorder is causing fragmented sleep.

Treatment for sleep fragmentation generally involves treating any underlying sleep disorders like narcolepsy or sleep apnea.

Sleep physicians generally recommend that people with unwanted nighttime awakenings work to improve their sleep hygiene:

  • Go to bed and wake up at the same time each day
  • Avoid electronics in the last hour before bed
  • Avoid alcohol, particularly in the last hour before bed
  • Avoid caffeine at least eight hours before bed
  • Sleep in a space that’s cool, dark and quiet

Supplements like valerian or melatonin may help reduce sleep fragmentation. Cognitive behavioral therapy, relaxation training, and sleep restriction therapy may also help treat fragmented sleep. Generally, the higher a person’s sleep drive (i.e. tiredness), the lower their risk for fragmented sleep, so therapies that increase homeostatic sleep drive can lead to a more restful, restorative slumber.

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