SLEEP MEDICINE
ANNOTATED BIBLIOGRAPHY

The following are short reviews of interesting and relevant papers from the sleep literature. Most of these articles have appeared in the past few years in the American Review of Respiratory and Critical Care Medicine, Chest and Sleep. Full text versions of these papers may be obtained in most medical libraries. You can expect that this section will be updated on a quarterly basis.

SLEEP PAPERS OF GENERAL INTEREST

TABLE OF CONTENTS
Birketvedt et al. Behavioral and neuroendocrine characteristics of the night-eating syndrome.
Douglas et al. Breathing during sleep in patients with obstructive lung disease.
Farney et al. Sleep-disordered breathing associated with long-term opioid therapy.
Gold et al. Inspiratory airflow dynamics during sleep win women with fibromyalgia
Van den Buick et al. Television viewing, computer game playing, and internet use and self-reported time to bed and time out of been in secondary-school children.

Birketvedt GS, Florholmen J, Sundsfjord J, Osterud B, Dinges D, Bilker W and Stunkard A. Behavioral and neuroendocrine characteristics of the night-eating syndrome. JAMA 1999;282:657-663. Includes editorial.
Night eating syndrome (NES) is characterized by morning anorexia, evening hyperphagia and insomnia, which typically occurs during periods of stress. Up to 27% of severely obese individuals may have the disorder. The present study showed that patients consumed more of their daily caloric intake at night than controls (56% vs. 15%) and had an average number of awakenings of 3.6 vs. 0.3 for controls. More than half of the awakenings resulted in eating episodes vs. none for the controls. Night eaters also had attenuation of the nocturnal rise in plasma melatonin and leptin levels and higher circadian levels of plasma cortisol.

Douglas NJ and Flenley DC; Breathing during sleep in patients with obstructive lung disease. Am Rev Respir Dis, 1990; 141:1055-1070. Somewhat dated review of the literature does provide some useful information from the older literature.

1. Earlier studies have shown patients with significant Chronic Obstructive Pulmonary Disease have P02s that may drop from 64 mm Hg during wakefulness to 58 in NREM sleep to 50 in REM sleep while PC02 increased from 48 to 58 mm Hg. Pulmonary artery pressure (PAP) increased by almost 20mmg Hg as well during sleep.
2. Ventilation is reduced in all phases of sleep compared to wake in both normals and Chronic Obstructive Pulmonary Disease patients. While the decrease may be mild in NREM there can be significant decreased in REM, especially during phasic periods.
3. One study in Chronic Obstructive Pulmonary Disease with nocturnal desaturations during sleep had impaired ventilatory responses to hypoxia and hypercapnia.
4. The major cause of hypoxemia during sleep in patients with Chronic Obstructive Pulmonary Disease is hypoventilation in REM sleep.
5. One study showed a close inverse correlation between
PAP and sleep induced hypoxemia, with a 1% fall in Sa02 leading to a 1 mm Hg rise in the PAP.
6. Chronic Obstructive Pulmonary Disease have an increased number of hypoxemic arousals
7. In normal subjects alveolar ventilation is about 40% lower in phasic REM sleep. In addition, there is marked diminution in hypoxic and hypercarbic ventilatory response. May be related to hypotonia of intercostal muscles.
8. Patients with both Chronic Obstructive Pulmonary Disease and Obstructive Sleep Apnea are more likely to develop pulmonary hypertension.

Van den Buick J; Television viewing, computer game playing, and internet use and self-reported time to bed and time out of been in secondary-school children. Sleep 2003;27:101-109.

Introduction; Recent studies in school age children have demonstrated that television viewing and a TV in a child’s room are associated with sleep disturbances. Another study linked interrupted sleep to use of mobile phones. The author postulates that TV viewing and computer use are not automatically limited in time like sports activities and may be associated with sleep disruption.

Methods; Author used a self-reported questionnaire given to 2546 adolescents who were in the first year of secondary school (average age of 13 years) and fourth year of secondary school (average age of 16 years). Students were asked if they had TVs, computer game consoles and Internet access in their rooms. Going out included social activities outside of the home and was on a 6-point scale with 1 being never and 6 being every day.

Results; Boys reported watching “significantly more television than girls…(and) there were no differences between boys and girls as far as Internet use was concerned but fourth-year students reported using the Internet…more than did first-year students.”

Boys go to bed significantly later than girls, on average. First-year students are less tired than average and fourth-year while fourth-years are more fatigued. Respondents that did more sports were less tired than those pupils doing fewer athletic activities. “Children with a TV set in their room went to bed significantly later on weekdays and weekend days and got up significantly later on weekend days…(and those) with a gaming computer in their room went to bed significantly later on weekdays…(and spent)… significantly less time in bed”

Conclusions
The author drew four; first…TV is not the only distraction from adequate sleep in children. Second, media use can be associated with negative sleep patterns. Third, media use may cause its sleep disruption because it is unstructured time as opposed to sports that have a defined start and finish parameter and, lastly, “while previous research ad found that reduced time in bed during the week leads to compensatory behavior during the weekend, the present study showed that this is not true for unstructured (media use) activities.

Gold A, Dipalo F, Gold M and Broderick J. Inspiratory airflow dynamics during sleep win women with fibromyalgia, SLEEP, 2004;27:459-465.

Fibromyalgia is a functional somatic syndrome manifested by fatigue and diffuse body aches and pains affecting approximately 6 million Americans. Fibromyalgia syndrome has many of the symptoms of associated with OSA including depression, cognitive deficits, GERD, fatigue and difficulty initiating and maintaining sleep. There appears to be an association between fibromyalgia and OSA . This descriptive study of consecutive female patients with fibromyalgia assessed inspiratory flow dynamics to see if they were similar to a matched group of women with the Upper Airways Resistance Syndrome (thought by many sleep researchers to be an early form of OSA). A recent study by the present authors demonstrated similarities (excepting the diffuse body aches and pains) between fibromyalgia patients and those with UARS.
The authors comment that airflow limitation on inspiration in both disorders results from increased upper-airway collapsibility during sleep and go on to postulate that “splinting” (presumably through CPAP or a dental appliance) the upper airway during sleep will improve symptoms of fibromyalgia just as in the case with UARS and OSA
Methods
the study was conducted on 28 female patients with fibromyalgia. Of great interest is that 4 patients reported snoring only occasionally and 10 did not snore at all. Sleep induced inspiratory flow limitation was defined as the plateau pressure occurring in spite of an increasing effort as manifested by a decreasing esophageal pressure. The authors then determined a Pcrit or a nasal mask measurement pressure at time the upper airway occluded during non REM sleep as an index of upper airway collapsibility
Results
Eleven of 28 patients with fibromyalgia had alpha-delta sleep. The 18 patients out of the study group that had a full night sleep study had an apnea hypopnea index of 2.4±4.5 events per hour (not diagnostic of sleep apnea) with an arousal index of 30±13.7 arousals per hour (moderately elevated) Only one of the patients met criteria for the standard diagnosis of OSA having an AHI of 17.7 events per hour. However, 96% of the patients with fibromyalgia had inspiratory flow limitation and treatment of this flow limitation with CPAP had significantly beneficial effects (Figure 5). Additionally, their data analysis the authors felt that flow limitation abnormalities demonstrated in these patients were the cause of the increased arousal index. The authors conclude that fibromyalgia and UARS have similar pathophysiologies.
Conclusion
Fibromyalgia and mild sleep apnea (UARS) have similar clinical features. The treatment of the upper airway flow limitation in these patients with CPAP improves symptoms.

Sergi M, Rizzi M, Braghiroli A, et al. Periodic breathing during sleep in patients affected by fibromyalgia syndrome. Eur Respir J 1999;14:203-2-8. Alvarez Lario B Alonso Valdivielso JL, Alegre Lopez J, Martel Soteres C, Viejo Banuelos JL, Maranon Cabello A. fibromyalgia syndrome: overnight falls in arterial oxygen saturation Am J Med 1996:101:54-60 May KP, West SG< Baker MR, Everett DW, Sleep apnea in male patients with the fibromyalgia syndrome Am J Med 1993;94:505-508

The following figure shows the beneficial effects of CPAP on this group of patients (one patient had a dental appliance that advanced the lower jaw) Note the significant improvement in all measured parameters.