Deep brain stimulation alters light phase food intake microstructure in rats.

Treatment of eating disorders like obesity or anorexia is challenging. Options are limited and new approaches desired. An interesting approach is the application of deep brain stimulation (DBS). The nucleus accumbens (NAcc) is part of the food reward system. A pilot study reported that DBS of the NAcc shell modulates food intake and body weight in rats. Underlying mechanisms such as the food intake microstructure are unknown so far. Normal weight female Sprague-Dawley rats were equipped with a custom-made DBS electrode placed unilaterally in the NAcc shell. Biphasic stimulation was performed for seven days. Body weight and food intake including the microstructure were assessed over the experimental period. Behavior was monitored manually. DBS tended to increase body weight gain (28.1 ± 5.4 g) compared to sham-stimulated controls (16.7 ± 3.4, P = 0.05) without affecting daily food intake (P > 0.05). Further analyses showed that light phase food intake was stimulated, whereas dark phase food intake was decreased in the DBS group (P < 0.05). During the light phase bout frequency (+50%), bout duration (+64%), meal duration (+71%) and overall time spent in meals (+92%) were increased in DBS rats (P < 0.05), while during the dark phase no alterations were observed (P > 0.05). Behavior did not show differences regarding overall eating and drinking behavior (including food/water approach), grooming or locomotion (P > 0.05). Summarized, although overall food intake was not changed by DBS, light phase food intake was stimulated likely via a reduction of satiation.

Treatment with the ghrelin-O-acyltransferase (GOAT) inhibitor GO-CoA-Tat reduces food intake by reducing meal frequency in rats.

The ghrelin acylating enzyme ghrelin-O-acyltransferase (GOAT) was recently identified and implicated in several biological functions. However, the effects on food intake warrant further investigation. While several genetic GOAT mouse models showed normal food intake, acute blockade using a GOAT inhibitor resulted in reduced food intake. The underlying food intake microstructure remains to be established. In the present study we used an automated feeding monitoring system to assess food intake and the food intake microstructure. First, we validated the basal food intake and feeding behavior in rats using the automated monitoring system. Afterwards, we assessed the food intake microstructure following intraperitoneal injection of the GOAT inhibitor, GO-CoA-Tat (32, 96 and 288 µg/kg) in freely fed male Sprague-Dawley rats. Rats showed a rapid habituation to the automated food intake monitoring system and food intake levels were similar compared to manual monitoring (P = 0.43). Rats housed under these conditions showed a physiological behavioral satiety sequence. Injection of the GOAT inhibitor resulted in a dose-dependent reduction of food intake with a maximum effect observed after 96 mg/kg (-27%, P = 0.03) compared to vehicle. This effect was delayed in onset as the first meal was not altered and lasted for a period of 2 h. Analysis of the food intake microstructure showed that the anorexigenic effect was due to a reduction of meal frequency (-15%, P = 0.04), whereas meal size (P = 0.29) was not altered compared to vehicle. In summary, pharmacological blockade of GOAT reduces dark phase food intake by an increase of satiety while satiation is not affected.

Temporal modulation transfer functions in auditory receptor fibres of the locust ( Locusta migratoria L.).

The temporal resolution of auditory receptors of locusts was investigated by applying noise stimuli with sinusoidal amplitude modulations and by computing temporal modulation transfer functions. These transfer functions showed mostly bandpass characteristics, which are rarely found in other species at the level of receptors. From the upper cut-off frequencies of the modulation transfer functions the minimum integration times were calculated. Minimum integration times showed no significant correlation to the receptor spike rates but depended strongly on the body temperature. At 20 degrees C the average minimum integration time was 1.7 ms, dropping to 0.95 ms at 30 degrees C. The values found in this study correspond well to the range of minimum integration times found in birds and mammals. Gap detection is another standard paradigm to investigate temporal resolution. In locusts and other grasshoppers application of this paradigm yielded values of the minimum detectable gap widths that are approximately twice as large than the minimum integration times reported here.

Dawn simulation and bright light in the treatment of SAD: a controlled study.

BACKGROUND: Some small controlled studies have found that dawn simulation is effective in treating seasonal affective disorder (SAD). With a larger sample size and a longer duration of treatment, we compared dawn simulation with bright light therapy and a placebo condition in patients with SAD. METHOD: Medication-free patients with SAD were randomly assigned to one of three conditions: bright light therapy (10,000 lux for 30 min, from 6:00 AM to 6:30 AM), dawn simulation (1.5 hour dawn signal from 4:30 AM to 6:00 AM peaking at 250 lux), and a placebo condition, a dim red light (1.5 hour dawn signal from 4:30 am to 6:00 AM peaking at 0.5 lux.) Over the subsequent 6 weeks, the subjects were blindly rated by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating-Seasonal Affective Disorder Version (SIGH-SAD). We modeled the profiles of the remissions (SIGH-SAD < or = 8) and response (> or =50% decrease in SIGH-SAD) to treatment over time using Cox proportional hazards models. RESULTS: The sample consisted of 95 subjects who were randomized to the three conditions: bright light (n = 33), dawn simulation (n = 31) and placebo (n = 31). Dawn simulation was associated with greater remission (p <.05) and response (p <.001) rates compared to the placebo. Bright light did not differ significantly from the placebo. Dawn simulation was associated with greater remission (p <.01) and response (p <.001) rates compared to the bright light therapy. The mean daily hours of sunshine during the week before each visit were associated with a significant increase in likelihood of both remission (p <.001) and response (p <.001). CONCLUSIONS: Dawn simulation was associated with greater remission and response rates compared to the placebo and compared to bright light therapy. The hours of sunshine during the week before each assessment were associated with a positive clinical response.

Representation of acoustic communication signals by insect auditory receptor neurons.

Despite their simple auditory systems, some insect species recognize certain temporal aspects of acoustic stimuli with an acuity equal to that of vertebrates; however, the underlying neural mechanisms and coding schemes are only partially understood. In this study, we analyze the response characteristics of the peripheral auditory system of grasshoppers with special emphasis on the representation of species-specific communication signals. We use both natural calling songs and artificial random stimuli designed to focus on two low-order statistical properties of the songs: their typical time scales and the distribution of their modulation amplitudes. Based on stimulus reconstruction techniques and quantified within an information-theoretic framework, our data show that artificial stimuli with typical time scales of >40 msec can be read from single spike trains with high accuracy. Faster stimulus variations can be reconstructed only for behaviorally relevant amplitude distributions. The highest rates of information transmission (180 bits/sec) and the highest coding efficiencies (40%) are obtained for stimuli that capture both the time scales and amplitude distributions of natural songs. Use of multiple spike trains significantly improves the reconstruction of stimuli that vary on time scales <40 msec or feature amplitude distributions as occur when several grasshopper songs overlap. Signal-to-noise ratios obtained from the reconstructions of natural songs do not exceed those obtained from artificial stimuli with the same low-order statistical properties. We conclude that auditory receptor neurons are optimized to extract both the time scales and the amplitude distribution of natural songs. They are not optimized, however, to extract higher-order statistical properties of the song-specific rhythmic patterns.

Urinary free cortisol and sleep under baseline and stressed conditions in healthy senior women: effects of estrogen replacement therapy.

The purpose of this study was to examine the effects of a mild 24-h stress (indwelling IV catheter) on cortisol and sleep in postmenopausal women, and to evaluate differences due to estrogen replacement therapy (ERT) status. This study, conducted in the General Clinical Research Center at the University of Washington Medical Center, examined sleep, cortisol and sleep-cortisol relationships in both baseline and stress conditions, and compared women on ERT with women not on ERT. Forty-two women (age=69.6 +/- 6.2 years [SD]), of whom 20 were on ERT, participated. Urinary free cortisol (UFC) levels and sleep polysomnography were measured over both 24-baseline and stress condition. Sleep was impaired in the stress condition for both groups; mean UFC levels were higher, sleep efficiency and minutes of stages 2, 3 and 4 sleep were reduced, and morning risetime was earlier in the stress than baseline condition. For the combined groups, age-controlled correlations between 24-h UFC and sleep were significant in both conditions: at baseline, UFC levels were associated with earlier time of rising and less REM sleep, and under stress with reduced sleep efficiency, there was reduced minutes of stages 2, 3, 4 sleep, reduced REM sleep, and an earlier risetime. The pattern of negative significant correlations between UFC and sleep/sleep timing remained when plasma estrogen was statistically controlled; however, when groups were examined separately, the significant negative UFC-sleep relationships were confined to the non ERT group. Elevated 24-h UFC is associated with impaired sleep and earlier awakening in older women not on ERT, but not in women on ERT.

Estrogen replacement therapy moderates the sleep disruption associated with nocturnal blood sampling.

STUDY OBJECTIVES: To determine whether chronic oral estrogen replacement therapy (ERT) (1) improves the sleep of older, non-symptomatic postmenopausal women; and (2) reduces the sleep disruption associated with a stressor (frequent remote nocturnal blood-sampling through an intravenous catheter). DESIGN: Descriptive, cross-sectional, secondary analysis of a larger study. SETTING: The General Clinical Research Center at the University of Washington Medical Center. PARTICIPANTS: Women aged 57-80 (mean age = 70) at least 5 years past menopause were recruited from the community. Hot flashes and significant sleep difficulties were exclusion criteria. The ERT group (n=37) consisted of women on chronic oral ERT for > or = 2 years. The NERT group (n=56) consisted of women not using estrogen (NERT) for > or = 2 years. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Following an adaptation night, polysomnographic measures were collected for 2 consecutive nights. A blood sample was collected every 20 minutes for the last 24 hours (including Night 2), through an intravenous catheter. The only group difference in sleep on the baseline (non-catheter) night was that NERT women had a shorter sleep latency. Sleep on the catheter night was characterized by increased wakefulness, longer sleep latency, and decreased REM sleep for both groups relative to the baseline. However, the impact of nocturnal blood sampling was much greater for NERT than for ERT women: they experienced significantly greater percent changes in more sleep-wake variables, particularly slow-wave sleep (SWS). CONCLUSIONS: In this cross-sectional study, the use of chronic oral ERT was associated with little effect on the sleep of older postmenopausal women not experiencing hot flashes, except in the presence of a challenge to sleep. ERT ameliorated the disruptive effect of nocturnal blood sampling on both objectively assessed and subjectively assessed sleep.

Sleep impairments in healthy seniors: roles of stress, cortisol, and interleukin-1 beta.

STUDY OBJECTIVES: Increased stress responsivity and a longer-lasting glucocorticoid increase are common findings in aging studies. Increased cortisol levels at the circadian nadir also accompany aging. We used 24 h free urine cortisol to assess these age changes in healthy seniors. We hypothesized that free cortisol levels would explain individual differences in age-related sleep impairments. DESIGN: The study compared sleep, cortisol, and sleep-cortisol correlations under baseline and "stress" conditions in men and women. SETTING: Subjects were studied in the General Clinical Research Center under baseline conditions and a mildly stressful procedure (24 h indwelling intravenous catheter placement). PARTICIPANTS: Eighty-eight healthy, nonobese subjects (60 women and 28 men) from a large study of successful aging participated in the study. Mean ages were 70.6 (+/-6.2) and 72.3 (+/-5.7) years for women and men, respectively. MEASUREMENTS: The 24 h urines were collected for cortisol assay (radioimmunoassay [RIA]); blood was sampled at three diurnal time points for assay (enzyme-linked immunosorbent assay [ELISA]) of interleukin-1 (IL-1) beta; sleep architecture and sleep electroencephalograms (EEGs) were analyzed (after an adaptation and screening night) on baseline and stress nights via polysomnography and EEG power spectral analysis. RESULTS: Healthy older women and men with higher levels of free cortisol (24 h urine level) under a mild stress condition had impaired sleep (lower sleep efficiency; fewer minutes of stages 2, 3, and 4 sleep; more EEG beta activity during non-rapid eye movement sleep [NREM] sleep). Similar results were obtained when stress reactivity measures were used (cortisol and sleep values adjusted for baseline values), but not when baseline values alone were used. Gender differences were apparent: Men had higher levels of free urine cortisol in both baseline and mild stress conditions. Cortisol and sleep correlated most strongly in men; cortisol stress response levels explained 36% of the variance in NREM sleep stress responses. In women, but not men, higher cortisol was also associated with earlier time of arising and less REM sleep. Higher cortisol response to stress was associated with increased circulating levels of IL-1beta, explaining 24% of the variance in a subset of women. CONCLUSION: These results indicate that free cortisol (as indexed by 24 h urine values) can index responses to mild stress in healthy senior adults, revealing functional correlations (impaired sleep, earlier times of arising, more EEG beta activity during sleep, more IL-1beta) and gender differences.

Glial hyperpolarization upon nerve root stimulation in the leech Hirudo medicinalis.

Hyperpolarizing responses in neuropil glial cells evoked by nerve root stimulation were studied in the central nervous system of the leech Hirudo medicinalis using intracellular recording and extracellular stimulation techniques. From a mean resting potential of -60.5 +/- 1.0, the glial membrane was hyperpolarized by -8.6 +/- 0.8 mV, via stimulation of the dorsal posterior nerve root in an isolated ganglion. Nerve root stimulation evoked biphasic or depolarizing responses in glial cells with resting potentials around -70 mV (Rose CR, Deitmer JW. J. Neurophysiol. 73:125-131, 1995). The hyperpolarizing response was reduced by the ionotropic glutamate receptor antagonist CNQX (50 microM) to 58% of its initial amplitude. In 15 mM Ca2+/15 mM Mg(2+)-saline the hyperpolarization was reduced by 44%. The hyperpolarization that persisted in high-divalent cation saline was not affected by CNQX. Bath-applied glutamate (500 microM) and kainate (2 microM) elicited glial hyperpolarizations that were sensitive to CNQX and 10 mM Mg2+/1 mM Ca(2+)-saline. The 5-HT-antagonist methysergide did not affect the hyperpolarizations evoked by nerve root stimulation. The results show that in the leech glial membrane responses to neuronal activity include not only depolarizations, as shown previously, but also hyperpolarizations, which are mediated by direct and indirect neuron-glial communication pathways. In the indirect pathway, glutamate is a transmitter between neurons.

Thyroid hormones: positive relationships with cognition in healthy, euthyroid older men.

BACKGROUND: Although the association of clinical hypothyroidism with cognitive deficits is well known, the cognitive effects of thyroid hormones in euthyroid subjects are less studied and understood. The purpose of this study was to examine thyroid-cognition relationships in healthy, euthyroid older men. METHODS: We examined healthy men (N = 44, mean age = 72), excluding clinically hypothyroid/hyperthyroid or diabetic/hyperglycemic subjects and those with dementia, depression, CNS medications, or recent illness. Plasma samples obtained across a 24-hour period were pooled, then assayed for total thyroxine (TT4), total triiodothyronine (TT3), and T3 resin uptake. Free thyroxine index (FT4I) was calculated. A broad cognitive battery (including the Wechsler Adult Intelligence Scale-Revised [WAIS-R], the Dementia Rating Scale [DRS], and the Rivermead Behavioral Profile [PROFILE]) was administered to all subjects. RESULTS: Regression analyses controlling age and education showed TT4 and FT4I to have significant positive relationships with measures of overall cognition; TT4 accounted for 8% to 12% of the variance in omnibus cognitive measures such as WAIS Performance, WAIS Verbal score, and GLOBAL cognitive scores. CONCLUSIONS: Our findings suggest that within "normal" range of variation in plasma thyroid hormones, TT4 but not T3 positively associates with general cognition in healthy elderly men.

Growth hormone in postmenopausal women after long-term oral estrogen replacement therapy.

Studies of estrogen effects on growth hormone (GH) and its pulsatile release in postmenopausal women have typically utilized estrogen replacement therapy (ERT) of relatively short duration (days to weeks). The purpose of this study was to compare GH measures from healthy postmenopausal women who were on oral ERT for 3 years or more (n = 24; mean ERT duration = 16.1 years) with women not on ERT (NERT; n = 40). Blood samples were drawn remotely every 20 min for 24 h and then analyzed for mean 24-h GH, mean GH during sleep, and mean 24-h insulin-like growth factor-I (IGF-I). GH peak analyses were also performed. Mean 24-h GH and GH during sleep were significantly higher and IGF-I was significantly lower in ERT women compared with NERT women. In addition, use of long-term ERT was associated with more GH peaks relative to women not on ERT, but no change in GH peak amplitude or area. GH was not related to age in either group. GH was strongly and negatively correlated with measures of adiposity in NERT women but not in ERT women. In conclusion, long-term oral ERT is associated with increased circulating GH and decreased IGF-I levels, even after many years of treatment.

Memory-scanning task performance in Alzheimer's disease.

Individuals with mild Alzheimer's Disease (AD) and healthy normal control (NC) older adults performed a varied-set version of the Sternberg memory-scanning task with Set Sizes 1, 2, 3, and 4. The AD group (N = 23) had slower and more variable reaction times (RT) than the NC group (N = 38). RT differences between groups were bigger for NO than for YES responses. The linear relationship between RT and set size was not as strong for the AD group as for the NC group. However, in contrast to earlier studies with fewer subjects, participants with AD and healthy older individuals did not differ in the rate at which they scan items in the memory set.

Potential applications of GH secretagogs in the evaluation and treatment of the age-related decline in growth hormone secretion.

The two classes of GH secretagogs--GH-releasing hormone (GHRH) and the GH-releasing peptides and their analogs (GHRP's)--retain their ability to endogenous GH secretion in healthy and frail elderly subjects. They have very limited utility in assessment of the state of the GH/IGF-I axis except to confirm an intact pituitary, but they are attractive potential alternatives to GH as therapeutic agents. There is wide interest in the possibility that elevating GH and IGF-I might increase muscle mass, physical strength and performance, and possible sleep and cognition in aging. The GH secretagogs, like GH, can produce a sustained stimulation of this axis; in contrast to GH, they preserve feedback regulation at the pituitary level and stimulate a near-physiologic pulsatile pattern of GH release. GHRP's and their nonpeptide analogs are also active when given orally, a significant practical advantage. Short-term treatment studies have shown that GHRH and the GHRP's can enhance GH secretion and elevate IGF-I and IGFBP-3 levels; that GHRH may promote sleep; and that these agents are generally well tolerated. Longer-term studies assessing effects upon body composition and physical and psychological function are underway.

Circadian temperature and cortisol rhythms during a constant routine are phase-delayed in hypersomnic winter depression.

Circadian temperature, cortisol, and thyroid-stimulating hormone (TSH) rhythms during a constant routine were assessed in 6 female controls and 6 female patients with hypersomnic winter depression (seasonal affective disorder, SAD) before and after morning bright light treatment. After sleep was standardized for 6 days, the subjects were sleep-deprived and at bed rest for 27 hours while rectal temperature, cortisol, and TSH levels were assessed. The minimum of the fitted rectal temperature rhythm was phase-delayed in the SAD group compared to the controls 5:42 AM vs. 3:16 AM (p < .005); with bright light treatment, the minimum advanced from 5:42 AM to 3:36 AM (p = .06). The minimum of the cortisol rhythm was phase-delayed in the SAD group compared to the control group, 12:11 AM vs. 10:03 PM (P < .05); with bright light treatment, the minimum advanced from 12:11 AM to 10:38 PM (P = .06) [corrected]. The acrophase of the TSH rhythm was not significantly phase-delayed in SAD subjects compared to control, though the trend appeared to be toward a phase-delay (p = .07). After bright light therapy, the TSH acrophase was not significantly different in the SAD subjects; the trend was a phase-advance (p = .09). Overall, the data suggest that circadian rhythms are phase-delayed relative to sleep in SAD patients and that morning bright light phase-advances those rhythms.

Successful 6-month endurance training does not alter insulin-like growth factor-I in healthy older men and women.

BACKGROUND: Lean body mass, strength, and endurance decline with advancing age, changes paralleled by declines in anabolic hormones, including growth hormone (GH) and insulin-like growth factor-I (IGF-I). Acute exercise has been shown to stimulate the GH/IGF-I axis, and long-term exercise increases GH. This study examined the effect of endurance training on IGF-I in healthy older men and women. METHODS: Thirty-one healthy older men (66.9 +/- 1.0 yrs, mean +/- SEM) and 21 healthy older women (67.1 +/- 1.7 yrs) were randomized to either 3d/wk, 6-month endurance (ET3) or stretching/flexibility (SF3) protocols. Another group of 15 healthy older men (69.0 +/- 1.3 yrs) participated in a more intensive 5d/wk, 6-month endurance protocol (ET5). Before and after training, subjects were weight stabilized and participated in maximal exercise tolerance testing, body composition assessment, and fasting blood sampling. RESULTS: ET3 training resulted in a significant increase (14%) in maximal aerobic power (VO2max), significant decreases in body weight (BW), fat mass (FM), and waist/hip ratio (WHR), and a significant increase in fat-free mass (FFM). No significant VO2max or body composition changes were observed in the SF3 group. For the ET5 group, a significant increase (22%) in VO2max and significant decrease in BW, FM, and WHR were observed. No significant changes in IGF-I were observed for any of the three groups. Pre- versus post-training IGF-I values were very stable (r = .86, p < .001) across subjects. CONCLUSIONS: Within-subject basal levels of IGF-I in healthy seniors were extremely stable between pre- and post-training assessments. Two endurance training protocols of magnitudes sufficient to significantly increase aerobic capacity and decrease measures of body adiposity did not significantly increase basal levels of IGF-I in healthy older men and women.

A study of the relationship between American sign language and English literacy.

This article presents the findings of a study of the relationship between American Sign Language (ASL) skills and English literacy among 160 deaf children. Using a specially designed test of ASL to determine three levels of ASL ability, we found that deaf children who attained the higher two levels significantly outperformed children in the lowest ASL ability level in English literacy, regardless of age and IQ. Furthermore, although deaf children with deaf mothers outperformed deaf children of hearing mothers in both ASL and English literacy, when ASL level was held constant, there was no difference between these two groups, except in the lowest level of ASL ability. The implication of this research is straightforward and powerful: Deaf children's learning of English appears to benefit from the acquisition of even a moderate fluency in ASL.

Objective sleep quality of healthy older men and women is differentially disrupted by nighttime periodic blood sampling via indwelling catheter.

Elucidation of sleep-endocrine relationships requires frequent blood sampling during sleep recording. Unfortunately, such sampling can itself affect sleep and indirectly, hormonal patterns. We examined the effect of catheterization and frequent nighttime blood sampling on the sleep of a large sample of healthy older men and women. A total of 113 healthy older [69.1 +/- 0.6 years, mean +/- standard error of the mean (SEM) adults (68 women and 45 men) were studied. Following an adaptation night sleep was recorded during an undisturbed night and a night of periodic blood sampling via i.v. catheter. Lights out and lights on were significantly delayed and advanced, respectively, on the catheterization night, resulting in a significantly shorter time in bed (TIB). Total sleep time and sleep efficiency were significantly reduced, and sleep latency, total wake time and the number of awakenings from sleep of > or = 1 minute were significantly increased. Rapid eye movement (REM) sleep percentage of TIB was significantly reduced. Stages 3/4 sleep [slow wave sleep (SWS)] percentage of TIB was significantly reduced, as was total delta energy during SWS. With the exception of total sleep time and sleep latency, all sleep-wake and delta variables were significantly correlated between nights. This was particularly the case for SWS and the delta energy variables. When examined separately by gender, both men and women showed significant catheter-based sleep disturbance. However, SWS and delta energy measures in men were unaffected by catheterization. The data clearly demonstrate that both the sleep maintenance and sleep architecture of healthy older men and women are significantly impacted by nighttime blood sampling procedures. Of the various measures examined here, SWS measures appear to be the least disrupted, particularly in men. These findings need to be taken into account in any study examining sleep-endocrine relationships utilizing older subjects.

Higher plasma IGF-1 levels are associated with increased delta sleep in healthy older men.

BACKGROUND: Sleep quality declines with age, with less time in deep or slow wave sleep (SWS) and reduced amplitude of the delta waves that characterize it. Age-related declines also occur in lean body mass, growth hormone (GH), and insulin-like growth factor 1 (IGF-1). These changes in sleep quality and anabolic status may be related, as administration of GH or growth hormone releasing hormone (GHRH) can enhance SWS and decrease awakenings in young men. Here we examine the relationship between plasma IGF levels and delta sleep quality in older men. METHODS: The sleep EEG of 30 healthy elderly men (64 +/- 6 yrs; range 50-75) was recorded on the second of 2 consecutive nights. Plasma samples were drawn within 3 weeks of EEG recording, and IGF levels were assayed by RIA after acid extraction. RESULTS: IGF explained 28% (semi-partial correlation coefficient r = .53; p = .003) of the variance in average delta energy per epoch of SWS, after age-related variance was removed. Higher IGF was associated with higher average delta energy. Similar results were obtained for total delta energy during SWS (r = .37, p = .04) 4nd time spent in SWS (r = .42, p = .02). Other measures of sleep quality (e.g., wakefulness, REM sleep) were not correlated with IGF. The IGF delta relationship was minimally influenced by moderator variables such as thyroxine (T3, T4), and/or body mass index (BMI). CONCLUSION: We conclude that age-adjusted IGF levels in healthy senior men co-vary significantly with SWS and the delta energy that characterizes it.

Sleep and sleep disorders in older adults.

Complaints of sleep disturbance increase with age. Objective sleep assessments using polysomnography reveal sleep impairments (increased wakefulness and arousal from sleep; decreased slow wave sleep) even in healthy seniors. Both polysomnographic sleep and subjective sleep worsen in the presence of health impairments related to drug use, pain, cardiovascular disease, diabetes, depression, or other emotional disorders. In addition to normal aging and chronic disease, sleep complaints can also result from poor sleep habits, specific occult disorders during sleep, or some combination of these factors. Occult disorders include sleep apnea syndrome, periodic leg movements, and restless legs syndrome during sleep. Diagnosis and treatment of these and other sleep disorders is discussed. Both pharmacological and nonpharmacological treatments are considered, with an emphasis on behavioral and educative treatment approaches.