Temporal dissociation between myeloperoxidase (MPO)-modified LDL and MPO elevations during chronic sleep restriction and recovery in healthy young men.

OBJECTIVES: Many studies have evaluated the ways in which sleep disturbances may influence inflammation and the possible links of this effect to cardiovascular risk. Our objective was to investigate the effects of chronic sleep restriction and recovery on several blood cardiovascular biomarkers. METHODS AND RESULTS: Nine healthy male non-smokers, aged 22-29 years, were admitted to the Sleep Laboratory for 11 days and nights under continuous electroencephalogram polysomnography. The study consisted of three baseline nights of 8 hours sleep (from 11 pm to 7 am), five sleep-restricted nights, during which sleep was allowed only between 1 am and 6 am, and three recovery nights of 8 hours sleep (11 pm to 7 am). Myeloperoxidase-modified low-density lipoprotein levels increased during the sleep-restricted period indicating an oxidative stress. A significant increase in the quantity of slow-wave sleep was measured during the first recovery night. After this first recovery night, insulin-like growth factor-1 levels increased and myeloperoxidase concentration peaked. CONCLUSIONS: We observed for the first time that sleep restriction and the recovery process are associated with differential changes in blood biomarkers of cardiovascular disease.

Benefits of napping and an extended duration of recovery sleep on alertness and immune cells after acute sleep restriction.

Understanding the interactions between sleep and the immune system may offer insight into why short sleep duration has been linked to negative health outcomes. We, therefore, investigated the effects of napping and extended recovery sleep after sleep restriction on the immune and inflammatory systems and sleepiness. After a baseline night, healthy young men slept for a 2-h night followed by either a standard 8-h recovery night (n=12), a 30-min nap (at 1 p.m.) in addition to an 8-h recovery night (n=10), or a 10-h extended recovery night (n=9). A control group slept 3 consecutive 8-h nights (n=9). Subjects underwent continuous electroencephalogram polysomnography and blood was sampled every day at 7 a.m. Leukocytes, inflammatory and atherogenesis biomarkers (high-sensitivity C-reactive protein, interleukin-8, myeloperoxidase, fibrinogen and apolipoproteins ApoB/ApoA), sleep patterns and sleepiness were investigated. All parameters remained unchanged in the control group. After sleep restriction, leukocyte and - among leukocyte subsets - neutrophil counts were increased, an effect that persisted after the 8-h recovery sleep, but, in subjects who had a nap or a 10-h recovery sleep, these values returned nearly to baseline. Inflammatory and atherogenesis biomarkers were unchanged except for higher myeloperoxidase levels after sleep restriction. The increased sleepiness after sleep restriction was reversed better in the nap and extended sleep recovery conditions. Saliva cortisol decreased immediately after the nap. Our results indicate that additional recovery sleep after sleep restriction provided by a midday nap prior to recovery sleep or a sleep extended night can improve alertness and return leukocyte counts to baseline values.

Sleep restriction increases white blood cells, mainly neutrophil count, in young healthy men: a pilot study.

OBJECTIVES: This study examines the effects of sleep restricted to four hours for three consecutive nights on blood parameters, known to be associated with cardiovascular risk, in young healthy men. MATERIAL AND METHODS: Eight young healthy men (age 24.5 +/- 3.3 years) were studied in the sleep restricted group. Nine young healthy men (age 24 +/- 2 years) were included in the control group and spent the days and nights in the sleep lab, while sleeping eight hours/night. One baseline night was followed by three nights of sleep restriction to four hours and by one recovery night of eight hours. Blood samplings were performed after the baseline night and after the third night of sleep restriction or without restriction for the control group. RESULTS: A significant increase in white blood cells (WBC) (5.79 +/- 1.05 vs. 6.89 +/- 1.31 10(3) cell/microl, p = 0.03), and neutrophils (3.17 +/- 0.69 vs 4.24 +/- 0.97 10(3) cell/microl, p = 0.01) was observed after the third night of sleep restriction. Other blood parameters were not affected. No significant variation was observed in the control group. CONCLUSION: Sleep restriction affected WBC count, mainly neutrophils, considered as risk factor for cardiovascular disease. Stress induced by the short term sleep restriction could be involved in this observation.

Effects of sleep restriction on cognition in women.

The aim of the present study was to investigate how three nights of sleep restriction affected cognitive functions in young and aged healthy women. Ten young (20-30 years) and ten aged (55-65 years) women participated to the study. After one baseline night (11 pm-07 am), their sleep was restricted to 4h per night (01-05 am) during three nights. A recovery night of 8h (11 pm-07 am) followed the sleep restriction. The neurobehavioural assessment included evaluation of Attention (Stroop, Trail Making test, Tests of Attentional Performance), Memory (Buschke, Logical Memory, PASAT, Brown Peterson), Addition of numbers and Abstraction (Wisconsin). Sleep restriction decreased significantly the speed of execution, particularly in the young women, without affecting the accuracy of the answers. This effect was the most significant on reaction times in simple tests. The more complex tasks (PASAT, Brown Peterson, Logical Memory, Addition of numbers, Wisconsin) were not affected. However, the inhibition of an automatic activity (Stroop test) and the formation of a memory trace (Buschke memory test) were disturbed in both young and older women.

Psychomotor vigilance task performance during total sleep deprivation in young and postmenopausal women.

The objective of this study was to investigate the effects of age on women's performance in the psychomotor vigilance task (PVT) during total sleep deprivation (SD). A total of 46 healthy women volunteered. They belonged to two age groups: young (n=34; age range 19-30 years; 12 without, and 22 with oral contraceptives (OC); early phase of the menstrual cycle) and older (n=12; age range 60-68; postmenopausal; without hormone therapy). During a 40-h total SD, the subjects performed the PVT and the Stanford Sleepiness Scale (SSS) at 2-h intervals. At baseline, the reaction speed of the young women was faster as compared to the older women (Mann-Whitney U-test p<0.01). During SD, all the PVT measures as well as the SSS scores changed similarly in the two age groups, when the baseline performance difference in favour of the young women was taken into account (area under curve analyses, Mann-Whitney U-tests n.s.). No age difference in the time course of the SD-related deterioration in PVT performance or subjective sleepiness was observed. OC use had no effects on any of the measures during SD. After recovery sleep, young women had higher subjective sleepiness scores than older women, the sleepiness scores being highest in young women not taking OCs. In conclusion, in women, aging has no effects on the amount or the time course of the decline in PVT performance caused by total SD. OC use does not significantly affect young women's PVT performance during SD in the early phase of the menstrual cycle.

Sleep restriction increases blood neutrophils, total cholesterol and low density lipoprotein cholesterol in postmenopausal women: A preliminary study.

OBJECTIVES: This study examines the effects of sleep restricted to 4h for three consecutive nights on blood parameters known to be associated with cardiovascular risk in healthy postmenopausal women. MATERIAL AND METHODS: Ten healthy postmenopausal women aged 55-65 years treated with hormonal replacement therapy (HT) were included in the study. After one baseline night, three nights of sleep restricted to 4h were performed and were followed by one recovery night of 8h. Blood samplings were performed after the baseline night and after the third night of sleep restriction. RESULTS: A significant increase in white blood cells (WBC), monocytes, neutrophils, total cholesterol, and low density lipoprotein cholesterol (LDL-c) was observed after the third night of sleep restriction. CONCLUSION: Sleep restriction to 4h of sleep for three consecutive nights affected two factors associated with cardiovascular risk in healthy postmenopausal women treated with HT.

Age modulates the effects of sleep restriction in women.

STUDY OBJECTIVES: To investigate how age influences the effects of 3 nights of sleep restriction in healthy women. DESIGN: After a baseline night, sleep was restricted to 4 hours during 3 consecutive nights. One recovery night followed the sleep restriction. SETTING: The sleep-restriction experiments were conducted under standardized conditions with continuous electroencephalographic ambulatory recordings. Before entering the study, the subjects underwent a polysomnographic recording for exclusion of sleep disorder and adaptation to the laboratory environment. PARTICIPANTS: Eleven young women (aged 20-30 years) and 10 older women (aged 55-65 years) were included in the study. INTERVENTION: The subjects were admitted to the sleep laboratory for 5 consecutive nights and days. After 1 baseline night, 3 nights of sleep restriction to 4 hours were performed and were followed by 1 recovery night of 8 hours. Continuous ambulatory electroencephalographic recordings were performed, as well as the Maintenance of Wakefulness Test (8:30 AM and 1:30 PM), the Stanford Sleepiness Scale, and the Psychomotor Vigilance Test. RESULTS: Young women were more affected by sleep restriction than were the older women. This was evidenced by more sleep onsets during the Maintenance of Wakefulness Test sessions in the young subjects, who also rated themselves more sleepy than the older women. CONCLUSIONS: Age influences the impact of sleep restriction on vigilance in women.

Women's sleep in health and disease.

A huge amount of knowledge about sleep has accumulated during the last 5 decades following the discovery of rapid eye movement (REM) sleep. Nevertheless, there are numerous areas of considerable ignorance. One of these concerns the particularities of sleep in women. Most basic and clinical studies have been performed in male subjects, and only very recently research groups around the world have addressed women's sleep in health and disease. In this review, we summarize the present knowledge on the influence of oestrogens on the brain and on the distinctive changes of sleep across the menstrual cycle, during pregnancy and menopause. In addition, studies in female rodents are reviewed as well as the knowledge on female peculiarities regarding the interactions between sleep regulation and age-related changes in circadian rhythms. We also address specific aspects of sleep loss and sleep disorders in women. Finally, very recent studies on the sociology of sleep are summarized and future directions in the field are discussed.