Nocturnal oxygen therapy does not improve snorers' intelligence.

STUDY OBJECTIVE: To determine whether nasal oxygen therapy at 2 L/min would (1) reverse nocturnal hypoxemia and (2) improve neuropsychologic function in men who snore heavily. DESIGN: To select heavy-snoring subjects for a treatment protocol, volunteers were screened for one night, breathing air the first half and oxygen the second half of the night. If nocturnal oxygen desaturation occurred in the first half and was improved in the second half of the night, the subject entered a two-month treatment program. In random order, either nocturnal air or nocturnal oxygen was administered for one month each at 2 L/min in a double-blind crossover design. Neuropsychologic testing was done before and after each month. SETTING: Oxygen concentrators were modified to produce either greater than 96 percent oxygen or air at 2 L/min. Machines were delivered to the home of the subject and the machines were used each night, administering inspirate by nasal cannula. PARTICIPANTS: Seventeen asymptomatic men who snored heavily and volunteered for minimal payment of $75. INTERVENTIONS: Air was administered for one month, and oxygen was administered for one month. MEASUREMENTS AND RESULTS: On the screening night, oxygen administration did not improve obstructive sleep apnea, but did improve oxygenation. After one month of oxygen therapy at night, there was no significant benefit to multiple measures of neuropsychologic function. CONCLUSION: In this study, oxygen therapy at night had no effect on neuropsychologic function in men who snore heavily.

Sleep-disordered breathing and its concomitants in a subclinical population.

In order to evaluate possible deficits accompanying sleep-disordered breathing (SDB) in a subclinical population, the nocturnal respiration, health status, and sleep/wake cycle of 46 healthy, heavy-snoring men were measured. Sixty-two percent of these subjects had at least one episode of apnea/hypopnea, while 13% had high levels of apnea/hypopnea [apnea/hypopnea index (AHI) greater than or equal to 5]. Most events occurred in stages 1 or 2 or in REM sleep. Strong relationships between weight and SDB were observed, as were more modest relationships between age and SDB. Correlational procedures indicated relationships between SDB and higher blood pressure, subjective sleepiness, and napping. Because similar, but stronger, relationships involving these variables are observed in patients with a sleep apnea syndrome (SAS), it appears that a continuum exists between heavy-snoring men and patients with SAS. When these subjects were grouped by level of SDB, subjects with high levels of SDB (AHI greater than or equal to 5) had significantly lower nocturnal oxygenation parameters than the remaining subjects. However, there were no between-group differences in health or sleep/wake variables. It is concluded that while apnea/hypopnea events in subclinical populations may not be completely benign events, the level at which they may be considered frankly pathological is presently unclear.

Nocturnal hypoxia and neuropsychological variables.

Hypoxia is a well known cause of brain dysfunction. Neuropsychological impairments have been observed in normal subjects experiencing hypoxia iatrogenically as well as in patients with chronic lung disease. Recent investigations have demonstrated significant nocturnal hypoxia in subjects with sleep-disordered breathing. In the present study, heavy-snoring males, a group known to experience frequent episodes of sleep-disordered breathing received neuropsychological testing and a night of continuous monitoring of respiratory parameters. Partial correlations, controlling for age, weight, and education, indicated reliable relationships between nocturnal hypoxia and measures of general intelligence, verbal and nonverbal memory, and expressive verbal fluency. It is proposed that heavy-snoring males may potentially serve as a population in which to model the neurobehavioral effects of hypoxia. Further research in subjects with sleep-disordered breathing may help clarify the extent of the possible cognitive deficits as well as point out possible ameliorative treatments.