Warm Water Immersion Research Articles

Elevated core temperature in addition to mental fatigue impairs aerobic exercise capacity in highly trained athletes in the heat

The purpose of this study was to investigate the effects of elevated core temperature by exposure to heat stress vs. heat exposure without elevated core temperature (mean skin temperature only) in addition to mental fatigue on aerobic exercise capacity in the heat. Seven highly trained athletes completed two experimental conditions: elevation in core and skin temperatures (hyperthermia: HYP), and skin temperatures (SKIN). Participants performed the AX-Continuous Performance Task and Stroop Task to induce mental fatigue during a warm water immersion at 40 °C (HYP) and a passive seated heat exposure in a climatic chamber at 35 °C and 60% relative humidity (SKIN) for 45 min before exercise. Thereafter, participants performed running trial at 80% maximal oxygen uptake until voluntary exhaustion in the same chamber as the SKIN. Exercise time to exhaustion was significantly shorter in the HYP trial (538 ± 200 s) than in the SKIN trial (757 ± 324 s). Rectal temperature at the end of tasks in the HYP trial increased by 0.86 ± 0.26℃ and was significantly higher (37.69 ± 0.18℃) than that of the SKIN trial (36.96 ± 0.13℃), albeit no significant differences in mean skin temperature. Self-reported mental fatigue using visual analog scale was significantly higher after tasks in both trials, but no significant difference between trials was found. Throughout the trial, salivary cortisol concentration and perceptual responses were not affected by hyperthermia. This study demonstrated that a combination of high core temperature and mean skin temperature, and mental fatigue limit aerobic exercise capacity in highly trained athletes in hot environments compared with heat exposure without an elevation of core temperature.

The Effect of Post-Exercise Warm Water Immersion on Anaerobic Power Performance in College Students

Background/Objectives: The purpose of this study was to investigate the effect of a short-term passive post-exercise heat acclimation (HA) protocol on anaerobic performance in college students. Methods: In total, 28 participants (age 22.3 ± 2.1 years, height 168 ± 9.1 cm, mass 71.5 ± 16.6 kg) volunteered and were randomly divided into either an intervention (INT) or control (CON) group. Both groups followed a consecutive two-day protocol, consisting of a 25 min submaximal cycle @ 50–60% heart rate reserve (HRR), followed by a 25 min hot water immersion (INT) or nothing (CON). All participants performed a 30 s Wingate Anaerobic Test (WAnT) on four separate occasions—familiarization, pre-intervention, acutely post-intervention, and 24 h post intervention. The WAnT measured their peak power (W), relative peak power (W/kg), mean power (W), fatigue index (%), and total work (kJ). Results: From the results of the Factorial ANOVA, it was found that there were no significant differences, with no main effect for group (INT vs. CON) or time (Trials 1–4) and no significant interaction across all measured variables (p > 0.05). Conclusions: A two-day post-exercise passive HA protocol utilizing hot water immersion had no significant effect on the measurement of anaerobic performance in college students.

Phase-contrast Magnetic Resonance Angiography of Foot at Ultra-high field 5 T System: Visualization of Distal Small Vessels and Enhancement by Warm Water Immersion

Ultra-high field strength MR system has been proved to offer improved visualization of the distal intracranial vessels and branches, but its effectiveness on peripheral vasculatures was not investigated. We aim to assess the visualization of lower-extremity vessels using three-dimensional phase contrast MR angiography (3D PC-MRA) at 5T field-strength through the feet with warm water immersion (WWI). Participants were prospectively recruited and underwent 3T, 5T 3D PC-MRA on feet with and without WWI (water temperature between 40 to 45 ℃ for a duration of 10minutes). Patients with suspected lower-extremity vessel diseases underwent CTA for lesion identification. Signal-to-noise ratio (SNR), subjective scoring, quantitative vessel segmentation and flow velocity were performed to assess vessel visualization before and after WWI. Friedman's test was conducted to determine statistical significance. Out of thirty participants (mean age, 46.2±5.9; males, 20; lower-extremity vessel disease, 10), 900 vessel segments were available for evaluation. 5T images showed significantly higher scores of image quality and foot vessel visualization than 3T (all P <.05). WWI further improved the visualizing scores (percentage of score 3: 40.2% vs 66.2%, P =.008), SNR (44.27 vs 67.78, P <.001), total branch count (151.92 ± 29.17 vs 225.63 ± 16.76; P <.001), and the flow velocity (0.72 ± 0.03 vs 0.48 ± 0.11cm/s; P <.001). 3D PC-MRA at 5T effectively visualizes foot vessels in patients with lower-extremity disease. Furthermore, WWI can significantly enhance the depiction of distal and small vessels.

Heat Acclimation By Warm-water Immersion Enhances Whole-body Heat Loss In Older Adults

Heat Acclimation By Warm-water Immersion Enhances Whole-body Heat Loss In Older Adults

FLEXIBLE DUODENAL MONOCANNULA OF THE NATIONAL AGRICULTURAL AND FOOD CENTRE DESIGN FOR THE DETERMINATION OF INTESTINAL NUTRIENT DIGESTIBILITY IN CATTLE

Research in physiology of ruminant nutrition using the in sacco and mobile bag methods and developing and testing of a duodenal cannula of our own construction including our own surgical application in cattle, led to the intellectual property protection. The duodenal monocannula for determination of nutrient intestinal digestibility in cattle, designed by the National Agricultural and Food Centre (NPPC, Slovak Republic), has been registered by European Union intellectual property office, as a Registered Community Design. The innovativeness of the technical design of the "NPPC cannula" lies in the fact that the cannula is made of one piece of a straight tube with an inner diameter of 22 mm. The tube is smooth, with no additional extensions and glued parts. The operation does not require ligation of the bowel with an arterial prosthesis or a polyurethane felt. The dimensions of the cannula allow the use of the mobile bag method without any problems. The vinyl chloride emulsion was designed to polymerize at the lower temperature, than has been currently used in this procedure (130 °C), and the end used for fixation in the intestine could be shaped after immersion in warm water. During the growth of the animals, the tube length can be prolonged to adapt to the duodenal size. As a result, the life of cannulated animals can be extended without age limitation.

Maternal and neonatal outcomes among spontaneous vaginal births occurring in or out of water following intrapartum water immersion: The POOL cohort study.

Warm water immersion during labour provides women with analgesia and comfort. This cohort study aimed to establish among women using intrapartum water immersion analgesia, without antenatal or intrapartum risk factors, whether waterbirth is as safe for them and their babies as leaving the water before birth. Cohort study with non-inferiority design. Twenty-six UK NHS maternity services. A total of 73 229 women without antenatal or intrapartum risk factors, using intrapartum water immersion, between 1 January 2015 and 30 June 2022. The analysis excluded 12 827 (17.5%) women who received obstetric or anaesthetic interventions before birth. Non-inferiority analysis of retrospective and prospective data captured in NHS maternity and neonatal information systems. Maternal primary outcome: obstetric anal sphincter injury (OASI) by parity; neonatal composite primary outcome: fetal or neonatal death, neonatal unit admission with respiratory support or administration of antibiotics within 48 hours of birth. Rates of the primary outcomes were no higher among waterbirths compared with births out of water: rates of OASI among nulliparous women (waterbirth: 730/15 176 [4.8%] versus births out of water: 641/12 210 [5.3%]; adjusted odds ratio [aOR] 0.97, one-sided 95% CI, -∞ to 1.08); rates of OASI among parous women (waterbirth: 269/24 451 [1.1%] versus births out of water 144/8565 [1.7%]; aOR 0.64, one-sided 95% CI -∞ to 0.78) and rates of the composite adverse outcome among babies (waterbirth 263/9868 [2.7%] versus births out of water 224/5078 [4.4%]; aOR 0.65, one-sided 95% CI -∞ to 0.79). Among women using water immersion during labour, remaining in the pool and giving birth in water was not associated with an increase in the incidence of adverse primary maternal or neonatal outcomes.

Comparison of the Effectiveness of Kencur Warm Water Soaking with Salt Warm Water Against Leg Edema of Third Trimester Pregnant Women in the Working Area of Rawang Health Center, Indonesia

Leg edema is a common complaint in third trimester pregnant women. It is believed that soaking in kencur warm water and salt warm water can help overcome this. Comparing the effectiveness of soaking in warm kencur water with warm salt water on leg edema in third trimester pregnant women. Quasi-experimental research with a pretest-posttest design with the control group. A total of 60 third trimester pregnant women were divided into two groups: the kencur warm water immersion group (n=30) and the salt warm water immersion group (n=30). The intervention was carried out for 15 minutes, twice a day for 3 days. Leg edema was measured using a measuring tape before and after the intervention. There was a significant reduction in leg edema in both groups after intervention (p&lt;0.05). The reduction in leg edema in the kencur warm water immersion group was greater than in the salt warm water immersion group (p&lt;0.05). Kencur warm water soaks are more effective than salt warm water soaks in reducing leg edema in third-trimester pregnant women.

Choroidal Thickness Increases During Parasympathetic Dominance After Immersion of the Foot in Warm Water.

This study aimed to assess the course of changes in choroidal morphology after immersion of the foot in warm water at 40°C using enhanced depth imaging optical coherence tomography (EDI-OCT). Forty-three right eyes of 43 healthy participants were included. Changes in choroidal morphology were determined using EDI-OCT to evaluate subfoveal choroidal thickness (SCT). Systolic, diastolic, and mean blood pressures (SBP, DBP, and MBP, respectively) were also measured to determine systemic circulatory dynamics at baseline, immediately after immersion (0 min), and 10, 20, and 30 min after immersion. Immediately after immersion, SBP, DBP, and MBP were significantly declined versus baseline. In contrast, the SCT was significantly increased after warm water immersion. However, all these parameters did not change significantly compared to the baseline within 30 min. In the normal eye, parasympathetic nerve activity induced by warming stimuli increases choroidal morphology in response to a decrease in systemic circulatory activity, which normalizes within 30 min. The findings of this study may provide basic data for the prevention and treatment of various choroidal diseases in which sympathetic hyperactivity is involved in the pathogenesis.

Long-term effects of warm water immersion on kidney tissue damage in diabetic rats.

This study aimed to investigate the effects of Warm Water Immersion (WWI) on inflammation, kidney function, and kidney tissue damage in rats with diabetes mellitus (DM). Forty male rats were divided into four groups: Healthy Control (HC), Diabetic Control (DC), Diabetic Rats treated with WWI (DW), and Healthy Rats treated with WWI (HW). Daily 15-minute WWI sessions at 43 °C were administered for eight weeks. Various parameters including lipids, fasting blood sugar (FBS), HbA1C, insulin, advanced glycation end products (AGEs), HSP70, glomerular filtration rate (GFR), urinary albumin excretion, creatinine, blood urea nitrogen (BUN), oxidative stress, anti-oxidant parameters, and gene expression of RAGE, VEGF, and TGFß1 were assessed. Histological examination of kidney tissue was also conducted. Significant reductions in FBS, AGEs, glutathione, superoxide dismutase (SOD), and nitric oxide (NO) levels were observed in the DW group compared to DC. Expression of RAGE, VEGF, and TGFß1 genes decreased in DW. Triglycerides, total cholesterol, and LDL cholesterol were lower in DW. Insulin, HDL cholesterol, catalase, total anti-oxidant capacity (TAC), and tissue HSP70 were higher in DW. Histological assessment revealed reduced kidney damage in DW compared to DC. WWI for eight weeks shows promise in mitigating diabetic nephropathy in rats, suggesting its potential as a non-invasive adjunctive therapy for managing diabetes complications.

Parasympathetic Dominance Decreases the Choroidal Blood Flow Velocity Measured Using Laser Speckle Flowgraphy.

This study aimed to examine the changes to choroidal blood flow velocity using laser speckle flowgraphy (LSFG) in healthy eyes after warm water immersion at 40°C. Data regarding the right eyes of 23 healthy volunteers were included. The mean blur rate (MBR) of the macula, which represents the choroidal blood flow velocity, was evaluated using LSFG. Intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), ocular perfusion pressure (OPP), and MBR were assessed at baseline, immediately after immersion (0 minutes), and 10, 20, and 30 minutes later. At 0 minutes, SBP, DBP, MBP, and OPP values were lower than those at baseline. The MBR significantly declined immediately after immersion to -6.0 ± 5.2%. However, there were no changes in these parameters after 10, 20, or 30 minutes. A significant positive correlation was observed between the MBR, SBP, DBP, MBP, and OPP values. In healthy individuals, the dominant parasympathetic activity induced by warm stimulation reduced the choroidal hemodynamic rate in the macula and decreased systemic circulatory dynamics, which normalized after 10 minutes. These findings suggest that the dominant parasympathetic activity induced by warm water immersion at 40°C may lead to a reduction in the systemic circulation rate and choroidal blood flow rate in the macula. These findings may help prevent and treat various retinal choroidal diseases, in which sympathetic hyperactivity is involved in the pathogenesis of the disease.

Validation of a human thermoregulatory model during prolonged immersion in warm water

This study validates the Six Cylinder Thermoregulatory Model (SCTM) during prolonged warm water immersion, which underpins the Probability of Survival Decision Aid (PSDA) currently in use by the United States Coast Guard (USCG). PSDA predicts survival time for hypothermia and dehydration. USCG has been using PSDA for search and rescue operation since 2010. In 2019, USCG organized a workshop to review PSDA performance and concluded that PSDA is an essential tool for operation, although it occasionally overestimates survival times in warm waters above 16 °C. Forty-six human subjects were immersed from the neck down in 18, 22, and 26 °C water for 45 min up to 10 h. Rectal temperature (Tcore), 10-site mean skin temperature (Tsk), and water loss were measured. At the end of immersion, Tcore ranged from 35.2 to 38.0 °C, and Tsk ranged from 19.7 to 27.4 °C. The SCTM-predicted Tcore, Tsk and water loss were compared to the measured values. Root mean squared deviation (RMSD) was used to test for acceptable predictions. Tcore RMSDs were 0.2, 0.14, and 0.3 °C in 18, 22, and 26 °C water respectively. Tsk RMSDs were 1.44, 0.76, and 1.1 °C in 18, 22, and 26 °C water respectively. SCTM underpredicted water loss by 84%. Overall, SCTM predicted Tcore and Tsk with acceptable accuracy in 18 and 22 °C water for up to 10 h, but overpredicted in 26 °C water. Future studies and algorithm development are required to improve water loss prediction as well as Tcore and Tsk prediction in 26 °C water.

The Effect of Baby Spa on the Sleep Duration of Babies Aged 3-12 Months at Independent Midwife Practice (TPMB) Mrs. S, Karawang Regency, Indonesia

Baby spa is a series of treatments designed specifically for babies, providing gentle massages, immersion in warm water, and other sensory stimulation. This method is believed to help babies relax more, relieve muscle tension, improve blood circulation, and reduce colic. Gentle massage and immersion in warm water can help babies feel relaxed. This study aimed to determine the effect of baby spas on the sleep duration of babies aged 3-12 months at independent midwife practice (TPMB) Mrs. S, Karawang Regency, Indonesia. This study is experimental research with a pre-post-test approach with the control group. This study uses primary data, namely measuring the length of sleep of babies aged 3-12 months. A total of 30 research subjects took part in this study. In the intervention group, it was found that most babies slept in the range of 14-16 hours, which is considered the standard duration. Meanwhile, most of the control group had less than 14 hours, which is classified as a short sleep duration. In conclusion, baby spa influences the sleep duration of babies aged 3-12 months at independent midwife practice Mrs. S, Karawang Regency, Indonesia.

Hot water immersion: Maintaining core body temperature above 38.5°C mitigates muscle fatigue.

Hot water immersion (HWI) has gained popularity to promote muscle recovery, despite limited data on the optimal heat dose. The purpose of this study was to compare the responses of two exogenous heat strains on core body temperature, hemodynamic adjustments, and key functional markers of muscle recovery following exercise-induced muscle damage (EIMD). Twenty-eight physically active males completed an individually tailored EIMD protocol immediately followed by one of the following recovery interventions: HWI (40°C, HWI40 ), HWI (41°C, HWI41 ) or warm water immersion (36°C, CON36 ). Gastrointestinal temperature (Tgi ), hemodynamic adjustments (cardiac output [CO], mean arterial pressure [MAP], and systemic vascular resistance [SVR]), pre-frontal cortex deoxyhemoglobin (HHb), ECG-derived respiratory frequency, and subjective perceptual measures were tracked throughout immersion. In addition, functional markers of muscle fatigue (maximal concentric peak torque [Tpeak ]) and muscle damage (late-phase rate of force development [RFD100-200 ]) were measured prior to EIMD (pre-), 24 h (post-24 h), and 48 h (post-48 h) post-EIMD. By the end of immersion, HWI41 led to significantly higher Tgi values than HWI40 (38.8 ± 0.1 vs. 38.0°C ± 0.6°C, p < 0.001). While MAP was well maintained throughout immersion, only HWI41 led to increased (HHb) (+4.2 ± 1.47 μM; p = 0.005) and respiratory frequency (+4.0 ± 1.21 breath.min-1 ; p = 0.032). Only HWI41 mitigated the decline in RFD100-200 at post-24 h (-7.1 ± 31.8%; p = 0.63) and Tpeak at post-48 h (-3.1 ± 4.3%, p = 1). In physically active males, maintaining a core body temperature of ~25 min within the range of 38.5°C-39°C has been found to be effective in improving muscle recovery, while minimizing the risk of excessive physiological heat strain.

Elevated brain temperature under severe heat exposure impairs cortical motor activity and executive function

BackgroundExcessive heat exposure can lead to hyperthermia in humans, which impairs physical performance and disrupts cognitive function. While heat is a known physiological stressor, it is unclear how severe heat stress affects brain physiology and function. MethodsEleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal temperatures (Tre) attained 39.5°C, inducing exertional or passive hyperthermia, respectively. In a separate trial, blended ice was ingested before and during exercise as a cooling strategy. Data were compared to a control condition with seated rest (normothermic). Brain temperature (Tbr), cerebral perfusion, and task-based brain activity were assessed using magnetic resonance imaging techniques. ResultsTbr in motor cortex was found to be tightly regulated at rest (37.3°C ± 0.4°C (mean ± SD)) despite fluctuations in Tre. With the development of hyperthermia, Tbr increases and dovetails with the rising Tre. Bilateral motor cortical activity was suppressed during high-intensity plantarflexion tasks, implying a reduced central motor drive in hyperthermic participants (Tre = 38.5°C ± 0.1°C). Global gray matter perfusion and regional perfusion in sensorimotor cortex were reduced with passive hyperthermia. Executive function was poorer under a passive hyperthermic state, and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital cortex. Conversely, ingestion of blended ice before and during exercise alleviated the rise in both Tre and Tbr and mitigated heat-related neural perturbations. ConclusionSevere heat exposure elevates Tbr, disrupts motor cortical activity and executive function, and this can lead to impairment of physical and cognitive performance.

P1 - Immersing for a sense of coherence: casting a salutogenic lens over warm water immersion

P1 - Immersing for a sense of coherence: casting a salutogenic lens over warm water immersion

Subzero saline chilling with or without prechilling in icy water improved chilling efficiency and meat tenderness of broiler carcasses

Freshly slaughtered carcasses need to be chilled to improve product quality, meat safety, and processing efficiency. This research investigated the effect of subzero saline chilling (SSC) on broiler carcasses with or without prechilling in icy water. Water immersion chilling at 0.5°C (WIC) or SSC at 4% NaCl/-2.41°C (SSC) was a major chilling step. For the combination of pre- and postchilling, the warm water immersion chilling (WWIC) at 10°C was used as prechilling and the WIC as postchilling (WWIC-WIC), and WIC was used as prechilling and the SSC as postchilling (WIC-SSC). The internal temperature of breast fillets was monitored during chilling. Carcasses in a prechiller were transported to a postchiller when their internal temperature reached 15°C. Chilling was completed when the carcass temperature reached 4.4°C or below, and breast fillets were harvested at 3-h postmortem to measure the pH and sarcomere length. Color (L*, a*, and b*) values were evaluated on both breast skin and skinless breast surfaces. Meat tenderness was evaluated using the breast fillets after overnight storage and cooking to an internal temperature of 76°C. The carcasses in the SSC and WIC-SSC showed shorter chilling times (85-91 min) than those (100-144 min) of WIC and WWIC-WIC. A higher chilling yield was observed for the carcasses in WIC-SSC, and a lower cooking yield was seen for the carcasses in WWIC-WIC than other chilling methods (P < 0.05). The breast fillets of broilers in the SSC and WIC-SSC showed lower shear forces and longer sarcomere length than the WIC and WWIC-WIC. No difference was found for L* and a* values, while lower b* value was observed in the SSC than the other chilling methods (P < 0.05). Based on these results, chilling of broiler carcasses in the SSC (4% NaCl/-2.41°C) with or without prechilling in WIC at 0.5°C significantly improved chilling efficiency and meat tenderness, with minor color changes on carcasses.

Degradation and Microstructure of Palmdate Fibers-High Performance Cementitious Boards Exposed to Aging Conditions

It is essential to create more ecologically friendly and sustainable types of concrete due to severe emissions and the exhaustion of raw sources in cement manufacturing. The main objective was to determine if palmdate fibers were appropriate for use in wood-cement composite boards. A second objective is to improve the suitability of palmdate fibers for use in high-performance cementitious boards by pre-treatment procedures and carbon dioxide curing. The flexural strength and microstructural characteristics of the cement fiber boards were examined. In addition, durability tests including cycles of freezing and thawing, wetting and drying, and warm water immersion were also conducted. According to results, the use of treated palmdate fibers in high-performance cementitious boards was significant, because it increased flexural strength by 96%. Moreover, all CO2 cured boards showed higher flexural strength than control and pure carbonation curing 100% do not resulted in higher strength development. Also, X-ray diffraction patterns revealed, compared to control boards, CO2 cured boards showed more CaCO3 and lower Ca(OH)2 and according to SEM, aging exposures lead to make fibers rupture rather than pull out.

Penerapan Rendam Air Kencur Hangat Pada Kaki Untuk Mengurangi Edema Fisiologis Pada Asuhan Keperawatan Ibu hamil Di Puskesmas Kayamanya

Introduction : Pregnancy is the period that starts from conception to the birth of the fetus. During the pregnancy process, physical changes occur in pregnant women, one of which is physiological leg edema. So that one of the interventions that needs to be done in reducing physiological edema is by doing warm kencur water immersion therapy. The purpose of this study was to describe nursing care for pregnant women by applying warm kencur water immersion to reduce physiological edema at the Kayamanya Health Center. Method : The research method is using a descriptive research method with a case study approach of 1 third trimester pregnant woman patient with a characteristic of experiencing physiological leg edema and no pregnancy complications. Result : Research results Mrs. J complained of swelling in both legs, Mrs. J said that his legs often felt cramps, he often urinated and felt pain in his back area. Mrs. J often feels tired especially if he stands for too long. Mrs. J said he wanted to have a normal delivery, Mrs. J also always received support, motivation from her husband and family in facing childbirth. Nursing problems of discomfort, fatigue, and readiness for childbirth. The interventions were foot bath therapy, positioning, relaxation therapy, pregnancy care education, energy management, activity/rest education, and childbirth education. Implementation carried out for 5 days. Evaluation after implementation that the application of warm kencur water immersion can reduce physiological leg edema in third trimester pregnant women with decreased edema results, the patient appears more relaxed and comfortable, the patient is able to adapt to fatigue, the patient already understands about the delivery that will be faced. Conculsion : The conclusion that the application of warm kencur water soak is very effective in reducing leg edema. Suggestions that patients can do warm kencur water soak therapy independently according to what is taught by researchers

0163 Impact of cold-water hand immersion on cognitive performance and sleepiness during sleep inertia

Abstract Introduction Sleep inertia is a state of impaired cognitive performance upon awakening that dissipates with time awake. Manipulation of the distal-to-proximal skin temperature gradient using cold water has been hypothesized as a potential countermeasure to sleep inertia, but not previously explored (Krauchi et al., 2004). This study examined the effects of cold-water hand immersion on subsequent cognitive performance and sleepiness during sleep inertia. Methods Ten healthy adults (mean±standard deviation [SD] age 23.2±4.96 years; 6M, 4F) have thus far completed an ongoing 8-day protocol. Prior to an overnight in-laboratory visit, participants maintained habitual 8h sleep schedules for 1 week at home. In-laboratory sleep opportunities were timed to coincide with habitual sleep time. Following at least 5-min of electroencephalogram (EEG) verified continuous slow wave sleep (SWS), participants were awakened twice during the night to submerge their non-dominant hand in warm (34 C) or ice-cold water (0 C) for 3 min in a randomized, crossover design. Sleep inertia was assessed with a Mathematical Addition Test (ADD) and the Karolinska Sleepiness Scale (KSS) at ~ 5, 15, and 25 min after each awakening. Outcomes included number of correct responses and median reaction time for correct responses on the ADD and KSS scores. Data were analyzed with mixed-model ANOVA with condition, condition order and time since awakening as fixed factors and subject as a random factor. Results The average (Mean±SD) amount of SWS prior awakening was similar before the cold 7.0±2.3 min and warm 6.6±1.0min conditions (p&amp;gt;0.10). Following cold water immersion, subjective sleepiness was reduced and the median reaction time for correct responses was faster compared with warm water immersion (main effects of condition, p’s&amp;lt; 0.05). The number of correct responses was not significantly different between conditions, nor were there any significant interaction effects among the fixed factors. Conclusion These preliminary findings indicate that cold-water hand immersion may reduce sleepiness and increase the speed of arithmetic calculations during sleep inertia, which could have important implications for military and first responders performing after awakenings from sleep. Support (if any) Office of Naval Research MURI N00014-15-1-2809; NIH RHL165343A and CTSA Grant UL1 TR002535; Undergraduate Research Opportunities Grant, University of Colorado Boulder.

The sensory and affective components of pain differentially shape pupillary dilatation during cold pressor tests

Nociceptive and affective stimuli increase reflex sympathetic outflow to the pupils. To investigate effects of stimulus intensity, unpleasantness and distress on these pupillary reflexes, and to assess their stability, healthy participants immersed their hand in ice-water three times (for 20, 40 and 60s; or 60, 40 and 20s; or three times for 60s) (N=21 in each condition). Each ice-water immersion was preceded by a 90s warm water immersion. To evaluate phasic sympathetic influences on pupil diameter, pupillary re-dilatation after 1s of bright light was assessed during the last 10s of each immersion. By-and-large, pain ratings and pupil diameter were greater during longer than shorter ice-water immersions, and ice-water immersions facilitated pupillary re-dilatation after the flash stimulus. However, mean pupil diameter during ice- and warm water immersions, minor ipsilateral amplification of the pupillary response, and ratings of pain unpleasantness and distress decreased across the experiment. Together, these findings suggest that nociceptive input increased sympathetic pupillary tone and amplified phasic increases in sympathetic activity after exposure to light. However, tonic sympathetic influences on pupil diameter and lateralization decreased across repeated immersions, possibly as novel or threatening aspects of the experience declined. Pupillary nociceptive and affective reflexes involve the locus coeruleus, an integral component of neural circuits that heighten cortical arousal and regulate pain. As these reflexes appear to reflect different aspects of sensory and affective processing, their combined assessment might increase the sensitivity and specificity of tests of locus coeruleus function in patients with suspected deficits.