Abstract
Background:
The characterization of sleep in those with neurodegenerative disease (NDD) is essential in understanding the potential neurobiological mechanisms that underlie the connection between sleep disruption and NDD manifestations and progression.
Objective:
Explore the inter-relationships between NDD and age, sex, diagnosis of obstructive sleep apnea, snoring, and duration of sleep time with the head in the supine and non-supine positions.
Methods:
A case-control design was used to evaluate differences in sleep position obtained from multi-night, in-home Sleep Profiler recordings in 45 patients with diagnosed NDD (24 with mild cognitive impairment, 15 with Alzheimer’s disease, and 6 with Lewy Body, Parkinson’s, or other dementias) and 120 age-sex matched controls with normal cognition (NC).
Results:
The frequency of supine sleep >2 h/night was significantly greater in the NDD than in the NC group (p < 0.001, odds ratio = 3.7), and remained significant after controlling for age, sex, snoring, and obstructive sleep apnea diagnosis (p = 0.01). There were no group differences in nocturnal mobility i.e., number of head position changes/h.
Conclusion:
This study demonstrates the utility of in-home measurements of sleep in defining the association of supine sleep position with neurodegenerative disorders. Our findings warrant further investigation, particularly in light of the recent evidence suggesting that sleep may an active role in the brain’s ability to clear CNS neurotoxins and metabolites.
INTRODUCTION
Sleep abnormalities are highly prevalent in patients with neurodegenerative disease (NDD), often appearing in the pre-clinical stage long before cognitive decline or other objective neurological deficits are detected. The association between sleep disturbances and neurodegeneration may be bidirectional, as sleep disturbances may alternatively cause or result from neurodegenerative processes in the brain [1]. The presence of clinical sleep disorders has been linked with increased risk of future NDD, for instance, a recent study found patients with primary insomnia as young adults had a higher risk of developing dementia than those without primary insomnia [2]. Late-midlife obstructive sleep apnea (OSA) and short sleep duration has been linked to the manifestation of dementia in later life [3].
One mechanism suggested as underlying the relationship between sleep and NDD is the glymphatic system which clears soluble amyloid-β (Aβ) and likely other neurotoxic proteins from the brain, and which is selectively active during sleep [4–6]. Decreased sleep duration and disruption in nightly sleep have been shown to be associated with inefficient Aβ clearance, implying that sleep disturbance could lead to Aβ and other toxic proteins accumulating in the brain, potentially leading to an increased risk for neurodegeneration [7–9]. Even a single night of sleep deprivation was recently shown to lead to increased brain Aβ production, and acute sleep deprivation was also very recently shown to increase Aβ accumulation in the right hippocampus and thalamus, correlating with negative mood [7, 8, 10–13]. Gravity also affects the movement and distribution of blood out of the brain, and therefore characteristic sleep positions may also play a role in the efficiency of protein clearance from the brain [14–19].
The aim of this study was to conduct an exploratory investigation into the potential relationship between characteristic sleep patterns in a community dwelling NDD cohort in comparison to age-sex matched controls with normal cognitive function.
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