Investigation of pain sensitivity following 3 nights of disrupted sleep in healthy individuals

Background

Poor quality sleep is a common complaint among people with chronic pain. The co-occurrence of poor sleep quality and chronic pain often comes with increased pain intensity, more disability and a higher cost of healthcare. Poor sleep has been suggested to affect measures of peripheral and central pain mechanisms. To date, sleep provocations are the only models proven to affect measures of central pain mechanisms in healthy subjects. However, there are limited studies investigating the effect of several nights of sleep disruption on measures of central pain mechanisms.

Methods

The current study implemented three nights of sleep disruption with three planned awakenings per night in 30 healthy subjects sleeping at home. Pain testing was conducted at the same time of day at baseline and follow-up for each subject. Pressure pain thresholds were assessed bilaterally on the infraspinatus and gastrocnemius muscles. Using handheld pressure algometry, suprathreshold pressure pain sensitivity and area were also investigated on the dominant infraspinatus muscle. Cuff-pressure pain detection and tolerance thresholds, temporal summation of pain and conditioned pain modulation were investigated using cuff-pressure algometry.

Results

Temporal summation of pain was significantly facilitated (p = 0.022), suprathreshold pain areas (p = 0.005) and intensities (p < 0.05) were significantly increased, and all pressure pain thresholds were decreased (p < 0.005) after sleep disruption compared to baseline.

Conclusions

The current study found that three consecutive nights of sleep disruption at home induced pressure hyperalgesia and increased measures of pain facilitation in healthy subjects, which is consistent with previous findings.

Significance

Poor quality of sleep is often experienced by patients with chronic pain, with the most common complaint being nightly awakenings. This exploratory study is the first to investigate changes in measures of central and peripheral pain sensitivity in healthy subjects after sleep disruptions for three consecutive nights without any restrictions on total sleep time. The findings suggest that disruptions to sleep continuity in healthy individuals can induce increased sensitivity to measures of central and peripheral pain sensitization.     

The Effects of Recovery Sleep on Experimental Pain

Recent research suggests that recovery sleep (RS) has the potential to restore pain sensitivity and modulation after hyperalgesia due to preceding sleep deprivation. However, it has not yet been systematically examined whether the restoration of these pain parameters is driven by sleep characteristics of RS. Thus, the present study assessed changes in experimental pain during RS after total sleep deprivation (TSD) to test whether RS parameters predicted the restoration of the pain system. Thirty healthy participants completed one night of habitual sleep, one night of TSD and a subsequent recovery night. At-home sleep during baseline and recovery was assessed using portable polysomnography and a questionnaire. Before and after each night pressure pain thresholds (PPTs), temporal pain summation (TSP) and conditioned pain modulation (CPM) were assessed. PPTs decreased after TSD and increased following RS, indicating a restoration of pain sensitivity after hyperalgesia. RS characteristics did not predict this restoration, suggesting other mechanisms (eg, changes in serotonergic activity) underlying the observed pain changes. TSP indicated a lack of effect of experimental sleep manipulations on excitatory processes whereas CPM lacked sufficient reliability to investigate inhibitory processes. Thus, results indicate moderate effects of sleep manipulations on pain sensitivity, but not on pain modulation.PerspectiveThis article highlights the potential of recovery sleep to let pain thresholds return to normal following their decrease after a night of total sleep deprivation. In contrast, endogenous pain modulation (temporal pain summation, conditioned pain modulation) was not affected by sleep deprivation and recovery sleep.     

Evaluating effects of aromatherapy massage on sleep in children with autism: a pilot study

Previous studies have found beneficial effects of aromatherapy massage for agitation in people with dementia, for pain relief and for poor sleep. Children with autism often have sleep difficulties, and it was thought that aromatherapy massage might enable more rapid sleep onset, less sleep disruption and longer sleep duration. Twelve children with autism and learning difficulties (2 girls and 10 boys aged between 12 years 2 months to 15 years 7 months) in a residential school participated in a within subjects repeated measures design: 3 nights when the children were given aromatherapy massage with lavender oil were compared with 14 nights when it was not given. The children were checked every 30 min throughout the night to determine the time taken for the children to settle to sleep, the number of awakenings and the sleep duration. One boy's data were not analyzed owing to lengthy absence. Repeated measures analysis revealed no differences in any of the sleep measures between the nights when the children were given aromatherapy massage and nights when the children were not given aromatherapy massage. The results suggest that the use of aromatherapy massage with lavender oil has no beneficial effect on the sleep patterns of children with autism attending a residential school. It is possible that there are greater effects in the home environment or with longer-term interventions.     

The association between nocturnal hot flashes and sleep in breast cancer survivors

This study examined the relationship between objectively measured nocturnal hot flashes and objectively measured sleep in breast cancer survivors with insomnia. Twenty-four women who had completed treatment for non-metastatic breast cancer participated. All were enrolled in a study of cognitive–behavioral treatment for chronic insomnia. Nocturnal hot flashes and sleep were measured by skin conductance and polysomnography, respectively. The 10-minute periods around hot flashes were found to have significantly more wake time, and more stage changes to lighter sleep, than other 10-minute periods during the night. Nights with hot flashes had a significantly higher percentage of wake time, a lower percentage of Stage 2 sleep, and a longer REM latency compared to nights without hot flashes. Overall, hot flashes were found to be associated with less efficient, more disrupted sleep. Nocturnal hot flashes, or their underlying mechanisms, should be considered as potential contributors to sleep disruption in women with breast cancer who report poor sleep.     

Muscle pain induced by novel eccentric exercise does not disturb the sleep of normal young men

This experiment sought to determine if delayed-onset muscle pain following novel eccentric exercise would disrupt sleep. Nine young adult men performed eccentric exercise and, during a separate week, concentric exercise consisting of 8 sets of 10 repetitions at 80% of 1-repetition maximum for 3 muscle groups. Sleep was assessed polysomnographically the night before and 2 nights following the exercise bouts. Muscle pain intensity in the biceps, triceps, and quadriceps muscle groups was significantly increased following eccentric exercise (all P <.02), and upper arm range of motion was significantly decreased following eccentric exercise (F = 19.19; df [degrees of freedom] = 2,16; P <.0001). A Condition-by-Trial interaction was observed for stage 1 sleep (F = 6.91; df = 2,16; P =.007), and minutes of stage 1 sleep were reduced following eccentric exercise and increased following concentric exercise. In general, however, the hypothesized sleep disruptions following eccentric exercise were not observed. It is concluded that delayed onset muscle pain induced by novel eccentric exercise does not disturb the sleep of normal young men.     

Sleep,psychological distress,and stress arousal in women with fibromyalgia

The purpose of this investigation was to compare self-reported sleep quality and psychological distress, as well as somnographic sleep and physiological stress arousal, in women recruited from the community with self-reported medically diagnosed fibromyalgia (FM) to women without somatic symptoms. Eleven midlife women with FM, when compared to 11 asymptomatic women, reported poorer sleep quality and higher SCL-90 psychological distress scores. Women with FM also had more early night transitional sleep (stage 1) (p < 0.01), more sleep stage changes (p < 0.03) and a higher sleep fragmentation index (p < 0.03), but did not differ in α-EEG-NREM activity (a marker believed to accompany FM). No physiological stress arousal differences were evident. Less stable sleep in the early night supports a postulate that nighttime hormone (e.g., growth hormone) disturbance is an eitiologic factor but, contrary to several literature assertions, α-EEG-NREM activity sleep does not appear to be a specific marker of FM. Further study of mechanisms is needed to guide treatment options. © 1997 John Wiley & Sons, Inc. Res Nurs Health 20: 247–257, 1997     

Acute sleep deprivation is associated with increased electrocardiographic P-wave dispersion in healthy young men and women

Background: Sleep deprivation (SD) is associated with worse cardiovascular outcome including mortality. Prolonged P-wave duration and P-wave dispersion (Pd) are known to represent inhomogeneous conduction of sinus impulses and are known to be electrophysiologic predictors of atrial fibrillation. Pd in normal subjects has been reported to be influenced by the autonomic tone. Because autonomic tone is affected by sleep and sleep duration, we evaluated the effect of acute SD on P-wave duration and Pd in healthy young adults and whether the effect was gender selective.
Methods : We obtained electrocardiograms of 37 healthy young volunteers (age: 28.45 ± 7.97; 11 women) after a night of regular sleep and repeated after a night with sleep debt. We measured minimum and maximum P-wave durations (Pmin, Pmax) and Pd in milliseconds.
Results : Average sleep time of the subjects were 7.7 ± 0.8 hours during regular sleep and 1.7 ± 1.6 hours during a night of sleep debt (P < 0.001). Subjects had significantly lower values of Pmin in milliseconds after a night of sleep debt when compared to regular sleep (65.13 ± 8.03 vs 74.86 ± 10.95; P < 0.001), whereas they had significantly higher values of Pmax and Pd (102.16 ± 9.46 vs 95.13 ± 11.21; P < 0.001 and 37.02 ± 8.11 vs 20.27 ± 11.42; P < 0.001, respectively). In Pearson's correlation analysis Pmin was positively and Pmax and Pd were negatively correlated with sleep time (P < 0.001, r = 0.465; P = 0.003, r =−0.336 and P < 0.001, r =–0.698 respectively). Effect of SD on P-wave duration and Pd was similar for both men and women.
Conclusions : In conclusion, prolongation of Pmax and Pd in acute SD suggests that acute SD might contribute to development and/or recurrence of atrial fibrillation.     

Acute sleep deprivation is associated with increased QT dispersion in healthy young adults

Background: Sleep deprivation (SD) is known to be associated with worse cardiovascular outcome including mortality. We investigated the association between acute SD and electrocardiographic maximum QT interval (QTmax), QT, and corrected QT dispersion (QTd/cQTd), which are known to be among predictors of ventricular arrhythmias and sudden death.
Methods: We obtained electrocardiograms of 37 healthy young volunteers (age: 28.45 ± 7.97 years; 11 women) after a night with regular sleep and repeated after a night with sleep debt. We measured minimum QT interval (QTmin), QTmax, QTd, and cQTd in milliseconds.
Results: Average sleep time of the subjects were 7.7 ± 0.8 hours during regular sleep and 1.7 ± 1.6 hours during a night with sleep debt (P < 0.001). Subjects had similar values of QTmin in milliseconds after a night of sleep debt when compared to after regular sleep (347.56 ± 29.75 vs 344.59 ± 20.89; P = 0.51), whereas they had significantly higher values of QTmax, QTd, and cQTd (396.48 ± 30.11 vs 378.10 ± 23.90; P = 0.001, 49.45 ± 9.11 vs 33.51 ± 10.05; P < 0.001 and 54.92 ± 10.42 vs 37.23 ± 10.81; P < 0.001, respectively). In Pearson's correlation analysis, QTmax, QTd, and cQTd were inversely correlated with sleep time (P = 0.012, r =–0.291; P < 0.001, r =–0.625 and P < 0.001, r =–0.616, respectively)
Conclusions: In conclusion, we clearly demonstrated that even one night of SD is associated with significant increase in QTmax, QTd, and cQTd in healthy young adults despite remaining within normal limits. These electrocardiographic changes in acute SD might contribute to development and/or recurrence of arrhythmias. This implication deserves further studies for clarifying the possible linkage between SD and arrhythmias.     

Can modifications to the bedroom environment improve the sleep of new parents? Two randomized controlled trials

Postpartum sleep disruption is common among new parents. In this randomized controlled trial we evaluated a modified sleep hygiene intervention for new parents (infant proximity, noise masking, and dim lighting) in anticipation of night‐time infant care. Two samples of new mothers (n = 118 and 122) were randomized to the experimental intervention or attention control, and sleep was assessed in late pregnancy and first 3 months postpartum using actigraphy and the General Sleep Disturbance Scale. The sleep hygiene strategies evaluated did not benefit the more socioeconomically advantaged women or their partners in Sample 1, but did improve postpartum sleep among the less advantaged women of Sample 2. Simple changes to the bedroom environment can improve sleep for new mothers with few resources. © 2010 Wiley Periodicals, Inc. Res Nurs Health 34:7–19, 2011     

Activation of the prostaglandin system in response to sleep loss in healthy humans: Potential mediator of increased spontaneous pain

Insufficient duration of sleep is a highly prevalent behavioral pattern in society that has been shown to cause an increase in spontaneous pain and sensitivity to noxious stimuli. Prostaglandins (PGs), in particular PGE2, are key mediators of inflammation and pain, and we investigated whether PGE2 is a potential mediator in sleep-loss-induced changes in nociceptive processing. Twenty-four participants (7 females, age 35.1 ± 7.1 years) stayed for 7 days in the Clinical Research Center. After two baseline days, participants were randomly assigned to either 3 days of 88 h of sleep deprivation (TSD, N = 15) or 8 h of sleep per night (N = 9), followed by a night of recovery sleep. Participants rated the intensity of various pain-related symptoms every 2 h across waking periods on computerized visual analog scales. PGE2 was measured in 24-h-urine collections during baseline and third sleep deprivation day. Spontaneous pain, including headache, muscle pain, stomach pain, generalized body pain, and physical discomfort significantly increased by 5–14 units on a 100-unit scale during TSD, compared to the sleep condition. Urinary PGE2 metabolite significantly increased by about 30% in TSD over sleep condition. TSD-induced increase in spontaneous pain, in particular headache and muscle pain, was significantly correlated with increase in PGE2 metabolite. Activation of the PGE2 system appears to be a potential mediator of increased spontaneous pain in response to insufficient sleep.     

A warm footbath before bedtime and sleep in older Taiwanese with sleep disturbance

A single-group crossover design was used to examine the effects of a warm footbath on body temperatures, distal-proximal skin temperature gradient (DPG), and sleep outcomes in 15 Taiwanese elders with self-reported sleep disturbance. Body temperatures and polysomnography were recorded for three consecutive nights. Participants were assigned randomly to receive a 41 degrees C footbath for 40 minutes before sleep onset on night 2 or night 3. Mean DPG before lights off was significantly elevated on the bathing night. There were no significant differences in sleep outcomes between the two nights. However, when the first two non-rapid eye movement (NREM) sleep periods were examined, the amount of wakefulness was decreased in the second NREM period on the bathing night.     

One night of total sleep deprivation promotes a state of generalized hyperalgesia: A surrogate pain model to study the relationship of insomnia and pain

Sleep disturbances are highly prevalent in chronic pain patients. Understanding their relationship has become an important research topic since poor sleep and pain are assumed to closely interact. To date, human experimental studies exploring the impact of sleep disruption/deprivation on pain perception have yielded conflicting results. This inconsistency may be due to the large heterogeneity of study populations and study protocols previously used. In addition, none of the previous studies investigated the entire spectrum of nociceptive modalities. To address these shortcomings, a standardized comprehensive quantitative sensory protocol was used in order to compare the somatosensory profile of 14 healthy subjects (6 female, 8 male, 23.5 ± 4.1 year; mean ± SD) after a night of total sleep deprivation (TSD) and a night of habitual sleep in a cross-over design. One night of TSD significantly increased the level of sleepiness (P < 0.001) and resulted in higher scores of the State Anxiety Inventory (P < 0.01). In addition to previously reported hyperalgesia to heat (P < 0.05) and blunt pressure (P < 0.05), study participants developed hyperalgesia to cold (P < 0.01) and increased mechanical pain sensitivity to pinprick stimuli (P < 0.05) but no changes in temporal summation. Paradoxical heat sensations or dynamic mechanical allodynia were absent. TSD selectively modulated nociception, since detection thresholds of non-nociceptive modalities remained unchanged. Our findings show that a single night of TSD is able to induce generalized hyperalgesia and to increase State Anxiety scores. In the future, TSD may serve as a translational pain model to elucidate the pathomechanisms underlying the hyperalgesic effect of sleep disturbances.     

Longitudinal and Temporal Associations Between Daily Pain and Sleep Patterns After Major Pediatric Surgery

Approximately 20% of children develop persistent pain after major surgery. Sleep disruption has been implicated as a predictor of children's acute postsurgical pain. However, perioperative sleep patterns have not been longitudinally assessed, and the role of sleep in persistence of postsurgical pain has not been explored. We aimed to examine sleep patterns over 4 months in children having major surgery, and temporal relationships between daily sleep and pain. Sixty children age 10 to 18 (mean = 14.7) years having major surgery completed 7 days of actigraphy sleep monitoring (sleep duration, efficiency), twice daily electronic diaries (sleep quality, pain intensity, medication use), and validated questionnaires at presurgery, 2 weeks, and 4 months postsurgery. Generalized linear models, controlling for age, sex, naps, and medication, showed sleep quality (β [B] = ?.88, P < .001) and efficiency (B = ?1.50, P = .036) were significantly reduced at 2 weeks compared with presurgery, and returned to baseline by 4 months. Poorer night-time sleep quality was significantly associated with greater next day pain intensity (B = ?.15, P = .005). Sleep duration and efficiency were not associated with subsequent pain; daytime pain was not associated with subsequent sleep. Findings suggest sleep quality may be an important target for intervention after surgery in children; research is needed to understand how other sleep parameters may relate to recovery.

Sleep Quality,Affect, Pain,and Disability in Children With Chronic Pain: Is Affect a Mediator or Moderator?

Sleep problems have been identified as a potential antecedent of chronic pain and pain-related disability in pediatric populations. In adult studies, affect has been implicated in these relationships. This study sought to better understand the relationships between sleep quality, negative and positive affect, and pain and functioning in children with chronic pain. Participants included 213 children and adolescents (aged 7–17 years) presenting to a tertiary pain clinic with chronic pain. Children completed questionnaires measuring sleep quality, positive and negative affect, pain intensity, and functional disability. Results indicated that 74% of children reported disordered sleeping and that poor sleep quality was significantly associated with increased pain, disability, negative affect, and decreased positive affect. Our hypotheses were partially supported, with negative affect (but not positive affect) mediating the relationship between poor sleep and increased pain; and positive as well as negative affect mediating the relationship between poor sleep and increased functional disability. There was no evidence for affect as a moderator. This study adds to the growing literature demonstrating the effect of poor sleep quality on children's pain and functioning, highlighting the need to develop further longitudinal research to confirm the causal roles of these variables.

Sleep characteristics,exercise capacity and physical activity in patients with chronic fatigue syndrome

Abstract

Purpose: Unrefreshing sleep and lowered physical activity are commonly observed in chronic fatigue syndrome (CFS) patients, but how they might influence each other remains unexplored. Therefore, this study simultaneously examined the exercise capacity, sleep characteristics and physical activity in CFS patients. Methods: Handgrip strength and cycle exercise capacity were assessed in 42 female CFS patients and 24 inactive control subjects. During four consecutive days and nights, energy expenditure, activity and sleep–wake pattern were objectively registered using a Sensewear Armband. Results: Exercise capacity was significantly lower in CFS patients. In both groups VO₂peak correlated with the time subjects were physically active. In CFS patients only, VO₂peak correlated negatively with sleeping during the day whilst physical activity level and energy expenditure correlated negatively with sleep latency and lying awake at night. Conclusions: In the present study, CFS patients with higher VO₂peak tend to sleep less over day. Occupation in physical activities was negatively associated with sleep latency and lying awake at night. Increased physical activity potentially has beneficial effects on sleep quality in CFS. However, a close monitoring of the effects of increasing physical activity is essential to avoid negative effects on the health status of patients.

• Implications for Rehabilitation

• Female patients with chronic fatigue syndrome (CFS) have normal sleep latency and sleep efficiency, but sleep more and spent more time in bed as compared to healthy inactive women.

• Female CFS patients have lower exercise capacity, and a lower physical activity level as compared to healthy inactive women.

• CFS patients appear to be more sensitive for sleep quality (sleep latency and lying awake at night), which is associated with a low physical activity level.

     

Automatic activity of deep and superficial abdominal muscles during stable and unstable sitting positions in individuals with chronic low back pain

Objective

The purpose of this study was to assess muscle thickness changes in the deep and superficial abdominal muscles, during sitting on stable and unstable surfaces in subjects with and without chronic low back pain (CLBP).

Do earplugs stop noise from driving critical care patients into delirium?

ABSTRACT: Quality sleep is a problem for the critically ill who are cared for in an environment where interventions night and day are common, staff members are constantly present in relatively high numbers, and treatment is accompanied by a range of changing warning tones and alarms and lights. These critical care units are generally designed without a focus on patient comfort, sleep, and rest and often lack access to appropriate natural daylight. To add to this problem, critical illness, particularly sepsis, disrupts circadian rhythms and sleep patterns, and disruption of circadian rhythms, in turn, impairs immunity and contributes to delirium. In a randomized controlled trial in the previous issue of Critical Care, Van Rompaey and colleagues have intervened to reduce noise, which is a key factor in this disruption, by having patients use earplugs at night. Delirium was assessed by using the NEECHAM (Neelon and Champagne) confusion scale, and sleep perception was assessed by patients' responses to a set of five questions. After the first night, patients reported a better sleep perception and the occurrence of delirium was reduced (hazard ratio of 0.47 for the development of delirium) or was delayed. The study did not quantify adequacy of pain control in post-surgical patients and used patient reporting to assess sleep. Whether patients were receiving respiratory or other organ support was not reported. The potential benefit of earplugs is an important practical finding that could be implemented in most intensive care units.     

A randomized, controlled prospective trial of zolpidem and haloperidol for use as sleeping agents in pediatric burn patients.

Children with burn injuries often require hospital treatment where they are subjected to stimuli likely to produce sleep deprivation. Previously demonstrated sleep fragmentation and significantly reduced sleep stage 3/4 and rapid eye movement in this population led to a search for sleep-enhancing interventions. The purpose of this study was to evaluate the effects of selected therapeutic interventions on sleep architecture. Forty patients with a mean (+/-SEM) age of 9.4 +/- 0.7 years, mean total burn surface area of 50.1 +/- 2.9% and full thickness burns of 43.2 +/- 3.6% were randomly assigned to one of two treatment regimens using a blinded crossover design. Continuous polysomnographic recordings were obtained for six study periods. Each patient alternately received zolpidem one week and haloperidol the next, with the first monitored night conducted without medication. Zolpidem minimally increased the proportion of 3/4 and rapid eye movement sleep (0.81 +/- 0.16 vs 0.61 +/- 0.10 hrs, P = .02) but not total sleep time (4.8 +/- 0.3 vs 4.3 +/- 0.3 hrs on control nights, P = .1). Haloperidol significantly increased total sleep (5.3 +/- 0.3 vs 4.3 +/- 0.3 hrs on control nights, P = .02) and stage 2 sleep (3.3 +/- 0.3 vs 2.4 +/- 0.2 hrs, P = .001) compared with control nights. Both drugs slightly improved average sleep and wake period duration compared with control nights. Although sleep was somewhat improved by each test drug, there were no statistically significant differences between the drugs. Additional studies are needed to identify methods for improving restorative sleep postburn.     

Rotating Shiftwork Schedules: Can We Enhance Physician Adaptation to Night Shifts?

Objectives : To evaluate the effectiveness of a broad, literature-based night shiftwork intervention for enhancement of emergency physicians' (EPs') adaptation to night rotations. Methods : A prospective, double-blind, active placebo-controlled study was conducted on 6 attending physicians in a university hospital ED. Three data sets were collected under the following conditions: baseline, after active placebo intervention, and after experimental intervention. In each condition, data were collected when the physicians worked both night and day shifts. Measurements included ambulatory polysomnographic recordings of the main sleep periods, objective performance tests administered several times during the subjects' shifts, and daily subjective ratings of the subjects' sleep, moods, and intervention use. Results : The subjects slept an average of 5 hr 42 min across all conditions. After night shifts, the subjects slept significantly less than they did after day shifts (5 hr 13 min vs 6 hr 20 min; p < 0.05). The physicians' vigilance reaction times and times for intubation of a mannequin were significantly slower during night shifts than they were during day shifts (p = 0.007 and p < 0.04, respectively), but performances on ECG analysis did not significantly differ between night and day shifts. Mood ratings were significantly more negative during night shifts than they were during day shifts (more sluggish p < 0.04, less motivated p < 0.03, and less clear thinking p < 0.04). The strategies in the experimental intervention were used 85% of the time according to logbook entries. The experimental and active placebo interventions did not significantly improve the physician's performance, or mood on the night shift, although the subjects slept more after both interventions. Conclusions : Although the experimental intervention was successfully implemented, it failed to significantly improve attending physicians' sleep, performance, or mood on night shifts. A decrease in speed of intubation, vigilance reaction times, and subjective alertness was evident each time the physicians rotated through the night shift. These findings plus the limited sleep across all conditions and shifts suggest that circadian-mediated disruptions of waking neurobehavioral functions and sleep deprivation are problems in EPs.     

The effects of total and REM sleep deprivation on laser-evoked potential threshold and pain perception

We investigated the effects of total and rapid eye movement (REM) sleep deprivation on the thermal nociceptive threshold and pain perception using the objective laser-evoked potential (LEP) and the subjective visual analogue scale (VAS). Twenty-eight male adult volunteers were assigned into Control (CTRL), Total (T-SD), and REM (REM-SD) Sleep Deprivation groups. The T-SD and REM-SD volunteers were totally or selectively deprived of sleep for 2 and 4 consecutive nights, respectively. Pain parameters were measured daily during the experimental period. Volunteers were stimulated on the back of the hand by blocks of 50 diode laser pulses. Intensities increased between successive blocks, ranging from nonnoxious to noxious levels, and the LEP threshold was identified based on the evoked-response onset. Both the LEP threshold and VAS ratings were significantly increased after the second night of T-SD. No significant variations were observed in the REM-SD group, suggesting a predominant role for slow wave sleep rather than selective REM-SD in pain perception. Also, for both sleep-deprived groups, the mean values of the LEP threshold and VAS ratings showed a gradual increase that was proportional to the SD deprivation time, followed by a decrease after 1 night of sleep restoration. These findings demonstrate a hyperalgesic modification to pain perception (as reflected by the augmented VAS) and a concomitant increase in the LEP threshold following T-SD, an apparently contradictory effect that can be explained by differences in the ways that attention affects these pain measurements.