For many people, the central symptom of interrupted sleep is easily noticeable: waking up from sleep one or more times during the course of the night (or during the day for people who work a night shift).

The timing and length of these wakeful episodes can vary. A person may have only a few breaks in sleep or several. They may be awake for just a few minutes or for an extended period before transitioning back to sleep. A person may experience restless sleep, tossing and turning or feeling only half-asleep without drifting off into deeper rest.

Not all cases of interrupted sleep, though, are readily apparent to the sleeper. Some people experience very brief and minor awakenings or arousals during the night without realizing it. For example, people with obstructive sleep apnea (OSA) have repeated lapses in breathing that cause brief arousals from sleep. These respiratory arousals are short enough that people with OSA usually don’t usually know that they are happening.

With a condition like OSA or other situations in which sleep fragmentation is frequent but not noticed by the sleeper, excessive daytime sleepiness is likely to be a key symptom of interrupted sleep.

Why Does Interrupted Sleep Matter?

The implications of interrupted sleep can be significant with impacts not just on sleep quality but also numerous aspects of individual health.

People who have interrupted sleep tend not to get enough overall sleep. Research has found a strong correlation between sleep continuity and total sleep time, indicating that people with disturbed sleep are at a higher risk of not sleeping enough hours. Not surprisingly, problems with sleep maintenance are a frequent complaint among people with insomnia. Insufficient sleep can cause daytime sleepiness that detracts from school or work performance and heightens the risk of accidents while driving or operating machinery.

Even when it doesn’t reduce sleep quantity, a mounting body of evidence points to the harm of interrupted sleep. During healthy sleep, a person progresses through a series of sleep cycles, each of which is made up of distinct sleep stages. Repeated interruptions and awakenings can disrupt that process, causing far-reaching effects of disrupted sleep on brain function, physical health, and emotional well-being.

Multiple studies have identified sleep continuity as important to thinking, memory, and decision-making. While the exact mechanisms underlying sleep’s role in brain health are not fully understood, research points to uninterrupted sleep as promoting memory consolidation.

Sleep disruptions have also been associated with neurodegenerative disease including age-related cognitive impairment, Alzheimer’s dementia, and Parkinson’s Disease. Fragmented sleep is considered to be an early symptom of these conditions, but research suggests that it may also be a contributing factor to their development and/or progression.

In addition, repeated awakenings during sleep have been connected to mood disorders like depression. One study demonstrated a stronger correlation between interrupted sleep and a decreased positive mood compared to reduced total hours of continuous sleep. In addition, These issues were compounded with consecutive days of interrupted sleep, suggesting that the effect can accumulate over time.

Disrupted sleep can cause detrimental impacts on physical health as well. Otherwise healthy people  have been found to have higher sensitivity to pain after just two nights of fragmented sleep. The long-term inability to proceed through each sleep stage combined with the activation of multiple systems of the body during repeated awakenings has been tied to higher rates of cardiovascular disease, weight gain, and metabolic problems including type 2 diabetes. Disturbed sleep may also be connected to cancer risk, although further research is necessary to better understand the complexity of the relationship between sleep and cancer.

All of these potential effects of interrupted sleep on the brain and body indicate that healthy sleep means more than just sleeping enough hours; it also requires avoiding disruptions that inhibit sleep continuity.

DISCOVER THE GIFT OF SLEEP: HEALY WATCH