Heart rate variability rebound following exposure to persistent and repetitive sleep restriction.

While it is well established that slow-wave sleep electroencephalography (EEG) rebounds following sleep deprivation, very little research has investigated autonomic nervous system recovery. We examined heart rate variability (HRV) and cardiovagal baroreflex sensitivity (BRS) during four blocks of repetitive sleep restriction and sequential nights of recovery sleep. Twenty-one healthy participants completed the 22-day in-hospital protocol.

Chronic exposure to insufficient sleep alters processes of pain habituation and sensitization.

Chronic pain conditions are highly comorbid with insufficient sleep. While the mechanistic relationships between the 2 are not understood, chronic insufficient sleep may be 1 pathway through which central pain-modulatory circuits deteriorate, thereby contributing to chronic pain vulnerability over time. To test this hypothesis, an in-laboratory model of 3 weeks of restricted sleep with limited recovery (5 nights of 4-hour sleep per night followed by 2 nights of 8-hour sleep per night) was compared with 3 weeks of 8-hour sleep per night (control protocol).

Repeating patterns of sleep restriction and recovery: Do we get used to it?

Despite its prevalence in modern society, little is known about the long-term impact of restricting sleep during the week and 'catching up' on weekends. This common sleep pattern was experimentally modeled with three weeks of 5 nights of sleep restricted to 4h followed by two nights of 8-h recovery sleep. In an intra-individual design, 14 healthy adults completed both the sleep restriction and an 8-h control condition, and the subjective impact and the effects on physiological markers of stress (cortisol, the inflammatory marker IL-6, glucocorticoid receptor sensitivity) were assessed.

Sleep deprivation and stressors: evidence for elevated negative affect in response to mild stressors when sleep deprived.

Stress often co-occurs with inadequate sleep duration, and both are believed to impact mood and emotion. It is not yet known whether inadequate sleep simply increases the intensity of subsequent stress responses or interacts with stressors in more complicated ways. To address this issue, we investigated the effects of one night of total sleep deprivation on subjective stress and mood in response to low-stress and high-stress cognitive testing conditions in healthy adult volunteers in two separate experiments (total N = 53).

Sleep loss and inflammation.

Controlled, experimental studies on the effects of acute sleep loss in humans have shown that mediators of inflammation are altered by sleep loss. Elevations in these mediators have been found to occur in healthy, rigorously screened individuals undergoing experimental vigils of more than 24h, and have also been seen in response to various durations of sleep restricted to between 25 and 50% of a normal 8h sleep amount. While these altered profiles represent small changes, such sub-clinical shifts in basal inflammatory cytokines are known to be associated with the future development of metabolic syndrome disease in healthy, asymptomatic individuals.

Effects of sleep restriction on adiponectin levels in healthy men and women.

Objective: Population studies have consistently found that shorter sleep durations are associated with obesity and cardiovascular disease, particularly among women. Adiponectin is an adipocyte-derived, anti-inflammatory hormone that is related to cardiovascular disease risk. We hypothesized that sleep restriction would reduce adiponectin levels in healthy young adults.

Sleep restriction is associated with increased morning plasma leptin concentrations, especially in women.

Study Objectives: We evaluated the effects of sleep restriction on leptin levels in a large, diverse sample of healthy participants, while allowing free access to food.

Methods: Prospective experimental design. After 2 nights of baseline sleep, 136 participants (49% women, 56% African Americans) received 5 consecutive nights of 4 hours time in bed (TIB).

Differences in regional blood volume during a 28-day period of abstinence in chronic cannabis smokers.

Cerebral blood volume (CBV) studies have provided important insight into the effects of illicit substances such as cannabis. The present study examined changes in regional blood volume in the frontal and temporal lobe, and the cerebellum during 28 days of supervised abstinence from cannabis. Dynamic susceptibility contrast MRI (DSCMRI) data were collected on 15 current, long-term cannabis users between 6 and 36 h after the subjects' last reported cannabis use (Day 0), and again after 7 and 28 days of abstinence.

Increased amygdala fMRI activation after secretin administration.

It has recently been reported that secretin activates gene expression in the central nucleus of the amygdala in rats. To examine the neurophysiological effects of secretin on amygdalar activation in humans, the authors measured Blood Oxygen Level Dependent functional magnetic resonance imaging signal change during facial affect processing in a placebo-controlled double-blind study. The authors studied 12 healthy male subjects who were presented with three stimulus conditions: viewing happy, fearful, and neutral faces, before and after infusion with either secretin or placebo.

Altered regional blood volume in chronic cannabis smokers.

The quantitative measurement of cerebral perfusion is crucial for the study of both normal and impaired human brain function. Although cannabis is the most commonly abused illicit substance in the United States, its effects on cerebral blood volume (CBV) have not been fully examined. The objective of the present study was to examine differences in relative regional blood volume in focal regions of interest--including the frontal lobe, the temporal lobe, and the cerebellum--during a period of supervised abstinence from cannabis.

Lack of hippocampal volume change in long-term heavy cannabis users.

The effects of cannabis smoking on the morphology of the hippocampus are still unclear, especially because previous human studies have examined primarily younger, shorter-term users. We used magnetic resonance imaging to investigate these effects in a group of 22 older, long-term cannabis users (reporting a mean [SD] of 20,100 [13,900] lifetime episodes of smoking) and 26 comparison subjects with no history of cannabis abuse or dependence. When compared to control subjects, smokers displayed no significant adjusted differences in volumes of gray matter, white matter, cerebrospinal fluid, or left and right hippocampus.