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Enhance Sleep

April 2011

Effects of a tryptic hydrolysate from bovine milk alphaS1-casein on hemodynamic responses in healthy human volunteers facing successive mental and physical stress situations.

BACKGROUND: Preclinical results in rats have demonstrated anxiolytic-like effects of a tryptic bovine alphaS1-casein hydrolysate. AIM OF THE STUDY: We investigated the putative effects of this tryptic hydrolysate on systolic (SBP), diastolic (DBP) blood pressures, heart rate (HR) values and plasma cortisol concentrations (CC) in human healthy volunteers facing successive stress situations.

METHODS: The subjects were (double blind) randomly allocated to ingest three times, 12 hours apart, two capsules containing either 200 mg of alphaS1-casein hydrolysate (TS) or bovine skimmed milk powder as a placebo (CS). On the morning of the test day, a first blood sample for baseline measurement of CC was taken before the subjects were submitted to the Stroop test (ST) and, after a 30-min rest, to a Cold Pressor test (CPT). SBP, DBP, and HR were continuously recorded for 5 min before the ST and during each stress situation. A second blood sample was taken 15 min after the end of the CPT condition. RESULTS: ST and ST + CPT combined test situations increased SBP, DBP and HR. The significant “Treatment x SBP” and “Treatment x DBP” interactions indicated the lower percentage changes in SBP and DBP of the TS. In addition, the results showed a significant decrease of the CC in the TS but not in the CS throughout the ST + CPT combined stress tests. HR remained stable in TS between the initial rest period and the CPT unlike what happened in CS. CONCLUSION: On the basis of blood pressure and cortisol changes, these results suggest an antistress profile of this alphaS1-casein hydrolysate in human subjects.

Eur J Nutr. 2005 Mar;44(2):128-32.

Impact of sleep debt on metabolic and endocrine function.

BACKGROUND: Chronic sleep debt is becoming increasingly common and affects millions of people in more-developed countries. Sleep debt is currently believed to have no adverse effect on health. We investigated the effect of sleep debt on metabolic and endocrine functions. METHODS: We assessed carbohydrate metabolism, thyrotropic function, activity of the hypothalamo-pituitary-adrenal axis, and sympathovagal balance in 11 young men after time in bed had been restricted to 4 h per night for 6 nights. We compared the sleep-debt condition with measurements taken at the end of a sleep-recovery period when participants were allowed 12 h in bed per night for 6 nights. FINDINGS: Glucose tolerance was lower in the sleep-debt condition than in the fully rested condition (p<0.02), as were thyrotropin concentrations (p<0.01). Evening cortisol concentrations were raised (p=0.0001) and activity of the sympathetic nervous system was increased in the sleep-debt condition (p<0.02). INTERPRETATION: Sleep debt has a harmful impact on carbohydrate metabolism and endocrine function. The effects are similar to those seen in normal ageing and, therefore, sleep debt may increase the severity of age-related chronic disorders.

Lancet. 1999 Oct 23;354(9188):1435-9

The morbidity of insomnia uncomplicated by psychiatric disorders.

The morbidity of sleep problems has been well documented; however, they are frequently associated with and are symptomatic of several psychiatric disorders. It is unclear how much of the morbidity can be accounted for by the associated psychiatric and substance abuse disorders and medical problems, and how much by the sleep problems per se. Sleep problems may also be an early sign of a psychiatric problem. This paper reports data from an epidemiologic community survey of over 10,000 adults living in three US communities. A structured diagnostic assessment of psychiatric disorders as well as assessment of the presence of insomnia not due to medical conditions, medication, drug or alcohol abuse, and a 1-year follow-up were completed. Persons with insomnia in the past year without any psychiatric disorders ever (uncomplicated insomnia); with a psychiatric disorder in the past year (complicated insomnia); and with neither insomnia nor psychiatric disorders ever were compared on treatment utilization and the first onset of a psychiatric disorder in the subsequent year. Eight percent of those with uncomplicated as compared with 14.9% with complicated insomnia and 2.5% with neither had sought treatment from the general medical sector for emotional problems in the 6 months prior to the interview. The rates of treatment sought from the psychiatric specialty sector were 3.8%, 9.4%, and 1.2%, respectively. These differences were significant after controlling for sociodemographic characteristics and were sustained when the persons were interviewed 1 year later. Uncomplicated insomnia was also associated with an increase in risk for first onset of major depression, panic disorder, and alcohol abuse over the following year. Insomnia, even in the absence of psychiatric disorders, is associated with increased use of general medical and mental health treatment for emotional problems and for the subsequent first onset in the following year of some psychiatric disorders. Early diagnosis and treatment of uncomplicated insomnia may be useful.

Gen Hosp Psychiatry. 1997 Jul;19(4):245-50

Sleep loss results in an elevation of cortisol levels the next evening.

Sleep curtailment constitutes an increasingly common condition in industrialized societies and is thought to affect mood and performance rather than physiological functions. There is no evidence for prolonged or delayed effects of sleep loss on the hypothalamo-pituitary-adrenal (HPA) axis. We evaluated the effects of acute partial or total sleep deprivation on the nighttime and daytime profile of cortisol levels. Plasma cortisol profiles were determined during a 32-hour period (from 1800 hours on day 1 until 0200 hours on day 3) in normal young men submitted to three different protocols: normal sleep schedule (2300-0700 hours), partial sleep deprivation (0400-0800 hours), and total sleep deprivation. Alterations in cortisol levels could only be demonstrated in the evening following the night of sleep deprivation. After normal sleep, plasma cortisol levels over the 1800-2300-hour period were similar on days 1 and 2. After partial and total sleep deprivation, plasma cortisol levels over the 1800-2300-hour period were higher on day 2 than on day 1 (37 and 45% increases, p = 0.03 and 0.003, respectively), and the onset of the quiescent period of cortisol secretion was delayed by at least 1 hour. We conclude that even partial acute sleep loss delays the recovery of the HPA from early morning circadian stimulation and is thus likely to involve an alteration in negative glucocorticoid feedback regulation. Sleep loss could thus affect the resiliency of the stress response and may accelerate the development of metabolic and cognitive consequences of glucocorticoid excess.

Sleep. 1997 Oct;20(10):865-70

Sleep curtailment is accompanied by increased intake of calories from snacks.

BACKGROUND: Short sleep is associated with obesity and may alter the endocrine regulation of hunger and appetite. OBJECTIVE: We tested the hypothesis that the curtailment of human sleep could promote excessive energy intake. DESIGN: Eleven healthy volunteers [5 women, 6 men; mean +/- SD age: 39 +/- 5 y; mean +/- SD body mass index (in kg/m(2)): 26.5 +/- 1.5] completed in random order two 14-d stays in a sleep laboratory with ad libitum access to palatable food and 5.5-h or 8.5-h bedtimes. The primary endpoints were calories from meals and snacks consumed during each bedtime condition. Additional measures included total energy expenditure and 24-h profiles of serum leptin and ghrelin. RESULTS: Sleep was reduced by 122 +/- 25 min per night during the 5.5-h bedtime condition. Although meal intake remained similar (P = 0.51), sleep restriction was accompanied by increased consumption of calories from snacks (1087 +/- 541 compared with 866 +/- 365 kcal/d; P = 0.026), with higher carbohydrate content (65% compared with 61%; P = 0.04), particularly during the period from 1900 to 0700. These changes were not associated with a significant increase in energy expenditure (2526 +/- 537 and 2390 +/- 369 kcal/d during the 5.5-h and 8.5-h bedtime periods, respectively; P = 0.58), and we found no significant differences in serum leptin and ghrelin between the 2 sleep conditions. CONCLUSIONS: Recurrent bedtime restriction can modify the amount, composition, and distribution of human food intake, and sleeping short hours in an obesity-promoting environment may facilitate the excessive consumption of energy from snacks but not meals.

Am J Clin Nutr. 2009 Jan;89(1):126-33.

Metabolic effects of short-term elevations of plasma cortisol are more pronounced in the evening than in the morning.

To determine whether elevations of cortisol levels have more pronounced effects on glucose levels and insulin secretion in the evening (at the trough of the daily rhythm) or in the morning (at the peak of the rhythm), nine normal men each participated in four studies performed in random order. In all studies, endogenous cortisol levels were suppressed by metyrapone administration, and caloric intake was exclusively under the form of a constant glucose infusion. The daily cortisol elevation was restored by administration of hydrocortisone (or placebo) either at 0500 h or at 1700 h. In each study, plasma levels of glucose, insulin, C-peptide, and cortisol were measured at 20-min intervals for 32 h. The initial effect of the hydrocortisone-induced cortisol pulse was a short-term inhibition of insulin secretion without concomitant glucose changes and was similar in the evening and in the morning. At both times of day, starting 4-6 h after hydrocortisone ingestion, glucose levels increased and remained higher than under placebo for at least 12 h. This delayed hyperglycemic effect was minimal in the morning but much more pronounced in the evening, when it was associated with robust increases in serum insulin and insulin secretion and with a 30% decrease in insulin clearance. Thus, elevations of evening cortisol levels could contribute to alterations in glucose tolerance, insulin sensitivity, and insulin secretion.

J Clin Endocrinol Metab. 1999 Sep;84(9): 3082-92

Sleep-disordered breathing and mortality: a prospective cohort study.

BACKGROUND: Sleep-disordered breathing is a common condition associated with adverse health outcomes including hypertension and cardiovascular disease. The overall objective of this study was to determine whether sleep-disordered breathing and its sequelae of intermittent hypoxemia and recurrent arousals are associated with mortality in a community sample of adults aged 40 years or older. METHODS AND FINDINGS: We prospectively examined whether sleep-disordered breathing was associated with an increased risk of death from any cause in 6,441 men and women participating in the Sleep Heart Health Study. Sleep-disordered breathing was assessed with the apnea-hypopnea index (AHI) based on an in-home polysomnogram. Survival analysis and proportional hazards regression models were used to calculate hazard ratios for mortality after adjusting for age, sex, race, smoking status, body mass index, and prevalent medical conditions. The average follow-up period for the cohort was 8.2 y during which 1,047 participants (587 men and 460 women) died. Compared to those without sleep-disordered breathing (AHI: <5 events/h), the fully adjusted hazard ratios for all-cause mortality in those with mild (AHI: 5.0-14.9 events/h), moderate (AHI: 15.0-29.9 events/h), and severe (AHI: >or=30.0 events/h) sleep-disordered breathing were 0.93 (95% CI: 0.80-1.08), 1.17 (95% CI: 0.97-1.42), and 1.46 (95% CI: 1.14-1.86), respectively. Stratified analyses by sex and age showed that the increased risk of death associated with severe sleep-disordered breathing was statistically significant in men aged 40-70 y (hazard ratio: 2.09; 95% CI: 1.31-3.33). Measures of sleep-related intermittent hypoxemia, but not sleep fragmentation, were independently associated with all-cause mortality. Coronary artery disease-related mortality associated with sleep-disordered breathing showed a pattern of association similar to all-cause mortality. CONCLUSIONS: Sleep-disordered breathing is associated with all-cause mortality and specifically that due to coronary artery disease, particularly in men aged 40-70 y with severe sleep-disordered breathing.

PLoS Med. 2009 Aug;6(8):e1000132

Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies.

BACKGROUND: Increasing evidence suggests an association between both short and long duration of habitual sleep with adverse health outcomes. OBJECTIVES: To assess whether the population longitudinal evidence supports the presence of a relationship between duration of sleep and all-cause mortality, to investigate both short and long sleep duration and to obtain an estimate of the risk. METHODS: We performed a systematic search of publications using MEDLINE (1966-2009), EMBASE (from 1980), the Cochrane Library, and manual searches without language restrictions. We included studies if they were prospective, had follow-up >3 years, had duration of sleep at baseline, and all-cause mortality prospectively. We extracted relative risks (RR) and 95% confidence intervals (CI) and pooled them using a random effect model. We carried out sensitivity analyses and assessed heterogeneity and publication bias. RESULTS: Overall, the 16 studies analyzed provided 27 independent cohort samples. They included 1,382,999 male and female participants (followup range 4 to 25 years), and 112,566 deaths. Sleep duration was assessed by questionnaire and outcome through death certification. In the pooled analysis, short duration of sleep was associated with a greater risk of death (RR: 1.12; 95% CI 1.06 to 1.18; P < 0.01) with no evidence of publication bias (P = 0.74) but heterogeneity between studies (P = 0.02). Long duration of sleep was also associated with a greater risk of death (1.30; [1.22 to 1.38]; P < 0.0001) with no evidence of publication bias (P = 0.18) but significant heterogeneity between studies (P < 0.0001). CONCLUSION: Both short and long duration of sleep are significant predictors of death in prospective population studies.

Sleep. 2010 May 1;33(5):585-92

Sleep deprivation affects inflammatory marker expression in adipose tissue.

Sleep deprivation has been shown to increase inflammatory markers in rat sera and peripheral blood mononuclear cells. Inflammation is a condition associated with pathologies such as obesity, cancer, and cardiovascular diseases. We investigated changes in the pro and anti-inflammatory cytokines and adipokines in different depots of white adipose tissue in rats. We also assessed lipid profiles and serum levels of corticosterone, leptin, and adiponectin after 96 hours of sleep deprivation. METHODS: The study consisted of two groups: a control (C) group and a paradoxical sleep deprivation by 96 h (PSD) group. Ten rats were randomly assigned to either the control group (C) or the PSD. Mesenteric (MEAT) and retroperitoneal (RPAT) adipose tissue, liver and serum were collected following completion of the PSD protocol. Levels of interleukin (IL)-6, interleukin (IL)-10 and tumour necrosis factor (TNF)-α were analysed in MEAT and RPAT, and leptin, adiponectin, glucose, corticosterone and lipid profile levels were analysed in serum. RESULTS: IL-6 levels were elevated in RPAT but remained unchanged in MEAT after PSD. IL-10 protein concentration was not altered in either depot, and TNF-α levels decreased in MEAT. Glucose, triglycerides (TG), VLDL and leptin decreased in serum after 96 hours of PSD; adiponectin was not altered and corticosterone was increased. CONCLUSION: PSD decreased fat mass and may modulate the cytokine content in different depots of adipose tissue. The inflammatory response was diminished in both depots of adipose tissue, with increased IL-6 levels in RPAT and decreased TNF-α protein concentrations in MEAT and increased levels of corticosterone in serum.

Lipids Health Dis. 2010 Oct 30;9:125

Sleep restriction for 1 week reduces insulin sensitivity in healthy men.

OBJECTIVE: Short sleep duration is associated with impaired glucose tolerance and an increased risk of diabetes. The effects of sleep restriction on insulin sensitivity have not been established. This study tests the hypothesis that decreasing nighttime sleep duration reduces insulin sensitivity and assesses the effects of a drug, modafinil, that increases alertness during wakefulness. RESEARCH DESIGN AND METHODS: This 12-day inpatient General Clinical Research Center study included 20 healthy men (age 20-35 years and BMI 20-30 kg/m(2)). Subjects spent 10 h/night in bed for >or=8 nights including three inpatient nights (sleep-replete condition), followed by 5 h/night in bed for 7 nights (sleep-restricted condition). Subjects received 300 mg/day modafinil or placebo during sleep restriction. Diet and activity were controlled. On the last 2 days of each condition, we assessed glucose metabolism by intravenous glucose tolerance test (IVGTT) and euglycemic-hyperinsulinemic clamp. Salivary cortisol, 24-h urinary catecholamines, and neurobehavioral performance were measured. RESULTS: IVGTT-derived insulin sensitivity was reduced by (means +/- SD) 20 +/- 24% after sleep restriction (P = 0.001), without significant alterations in the insulin secretory response. Similarly, insulin sensitivity assessed by clamp was reduced by 11 +/- 5.5% (P < 0.04) after sleep restriction. Glucose tolerance and the disposition index were reduced by sleep restriction. These outcomes were not affected by modafinil treatment. Changes in insulin sensitivity did not correlate with changes in salivary cortisol (increase of 51 +/- 8% with sleep restriction, P < 0.02), urinary catecholamines, or slow wave sleep. CONCLUSIONS: Sleep restriction (5 h/night) for 1 week significantly reduces insulin sensitivity, raising concerns about effects of chronic insufficient sleep on disease processes associated with insulin resistance.

Diabetes. 2010 Sep;59(9):2126-33

The impact of daily sleep duration on health: a review of the literature.

A healthy amount of sleep is paramount to leading a healthy and productive lifestyle. Although chronic sleep loss is common in today’s society, many people are unaware of the potential adverse health effects of habitual sleep restriction. Under strict experimental conditions, short-term restriction of sleep results in a variety of adverse physiologic effects, including hypertension, activation of the sympathetic nervous system, impairment of glucose control, and increased inflammation. A variety of epidemiologic studies have also suggested an association between self-reported sleep duration and long-term health. Individuals who report both an increased (>8 h/d) or reduced (<7 h/d) sleep duration are at modestly increased risk of all-cause mortality, cardiovascular disease, and developing symptomatic diabetes. Although the data are not definitive, these studies suggest that sleep should not be considered a luxury, but an important component of a healthful lifestyle.

Prog Cardiovasc Nurs. 2004 Spring;19(2):56-9

Association of sleep duration with mortality from cardiovascular disease and other causes for Japanese men and women: the JACC study.

STUDY OBJECTIVES: To examine sex-specific associations between sleep duration and mortality from cardiovascular disease and other causes. DESIGN: Cohort study. SETTING: Community-based study. PARTICIPANTS: A total of 98,634 subjects (41,489 men and 57,145 women) aged 40 to 79 years from 1988 to 1990 and were followed until 2003. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: During a median follow-up of 14.3 years, there were 1,964 deaths (men and women: 1,038 and 926) from stroke, 881 (508 and 373) from coronary heart disease, 4,287 (2,297 and 1,990) from cardiovascular disease, 5,465 (3,432 and 2,033) from cancer, and 14,540 (8,548 and 5,992) from all causes. Compared with a sleep duration of 7 hours, sleep duration of 4 hours or less was associated with increased mortality from coronary heart disease for women and noncardiovascular disease/noncancer and all causes in both sexes. The respective multivariable hazard ratios were 2.32 (1.19-4.50) for coronary heart disease in women, 1.49 (1.02-2.18) and 1.47 (1.01-2.15) for noncardiovascular disease/noncancer, and 1.29 (1.02-1.64) and 1.28 (1.03-1.60) for all causes in men and women, respectively. Long sleep duration of 10 hours or longer was associated with 1.5- to 2-fold increased mortality from total and ischemic stroke, total cardiovascular disease, noncardiovascular disease/noncancer, and all causes for men and women, compared with 7 hours of sleep in both sexes. There was no association between sleep duration and cancer mortality in either sex. CONCLUSIONS: Both short and long sleep duration were associated with increased mortality from cardiovascular disease, noncardiovascular disease/noncancer, and all causes for both sexes, yielding a U-shaped relationship with total mortality with a nadir at 7 hours of sleep.

Sleep. 2009 Mar 1;32(3):295-301