The Role of Mood States Underlying Sex Differences in the Perception and Tolerance of Pain

Abstract:   While sex differences in pain reporting are frequently observed, the reasons underlying these differences remain unclear. The present study examined sex differences in self-report and physiological measures of pain threshold and tolerance following the administration of two laboratory pain-induction tasks. The primary study aim centered on determining whether repeated exposure to such tasks would yield sex differences in terms of pain threshold and tolerance. In addition, it was hypothesized that if such differences did exist, negative mood states might account for changes in pain ratings, threshold, and/or tolerance in subsequent exposure to noxious stimuli. Recruited from a convenience sample, 66 participants (44 female and 22 male) were exposed to both thermal and cold noxious stimuli at three separate times, while psychophysiological and self-report data were collected. Because women outnumbered men 2:1, Fisher z transformations were performed to determine whether the observed associations between mood states and pain ratings differed. We found stronger associations between fatigue and thermal-heat pain ratings for men at their first and third exposure to the pain task compared to women ( z  = 2.11, P  < 0.05; z  = 3.14, P  < 0.001, respectively). Results indicated that women evidenced greater pain tolerance than men on both a behavioral and physiological level; however, they reported greater pain severity than men. Fatigue was also found to be particularly important to reports of pain severity in men and pain tolerance in response to noxious stimuli for women. Possible pathways in which mood states influenced these endpoints are discussed.     

Altering gender role expectations: effects on pain tolerance, pain threshold, and pain ratings.

The literature demonstrating sex differences in pain is sizable. Most explanations for these differences have focused on biologic mechanisms, and only a few studies have examined social learning. The purpose of this study was to examine the contribution of gender-role stereotypes to sex differences in pain. This study used experimental manipulation of gender-role expectations for men and women. One hundred twenty students participated in the cold pressor task. Before the pain task, participants were given 1 of 3 instructional sets: no expectation, 30-second performance expectation, or a 90-second performance expectation. Pain ratings, threshold, and tolerance were recorded. Significant sex differences in the "no expectation" condition for pain tolerance (t = 2.32, df = 38, P <.05) and post-cold pressor pain ratings (t = 2.6, df = 37, P <.05) were found. Women had briefer tolerance times and higher post-cold pressor ratings than men. When given gender-specific tolerance expectations, men and women did not differ in their pain tolerance, pain threshold, or pain ratings. This is the first empirical study to show that manipulation of expectations alters sex differences in laboratory pain.     

Pain tolerance as a predictor of outcome following multidisciplinary treatment for chronic pain: differential effects as a function of sex

Sex-related differences in the experience of clinical and experimental pain have been widely reported. Females are at elevated risk for developing several chronic pain conditions and women demonstrate greater sensitivity to noxious stimulation in the laboratory. However, relationships between responses to experimental noxious stimuli and the experience of clinical pain have not been well characterized. One previous study of healthy adults indicated that pain threshold and tolerance were associated with clinical pain among women but not men (i.e. females with lower pain threshold and tolerance reported more clinical pain). In the present investigation, relationships between pain tolerance and outcomes of treatment for chronic pain were evaluated in a sex-dependent manner. Ischemic pain tolerance was assessed prior to treatment in 171 chronic pain patients completing a pain management program. Outcomes were measured as changes in pain severity, affect, and pain-related disability. Over the course of treatment, women demonstrated greater improvement in pain-related disability while men showed more reduction in pain. Ischemic pain tolerance was related to outcome in a sex-specific fashion. Women with higher pain tolerances showed greater improvement in pain, more reduction in pain-related interference, and more increases in activity level than women with lower pain tolerances. In contrast, pain tolerance was not associated with positive treatment outcomes among men. These results indicate that experimental pain responses may be most clinically relevant for women, and that sex differences may exist in the determinants of pain-treatment outcomes.     

Effects of subcutaneous administration of glutamate on pain, sensitization and vasomotor responses in healthy men and women

The present study aimed to investigate if (1) subcutaneous injection of glutamate induces pain, sensitization and vasomotor responses in humans and (2) if sex differences exist in these responses. Thirty healthy volunteers (men-15 and women-15) were included. Each subject received four subcutaneous injections (0.1ml; glutamate 100, 10, 1mM and isotonic saline 0.9%) into the forehead skin in two sessions separated by one week. Assessments of pain intensity (VAS), quality, distribution; area of pinprick hyperalgesia; pressure pain threshold (PPT) at the injection site; surface skin temperature and local blood flow were performed at predetermined time points. The highest concentration of glutamate evoked the highest pain intensity, the longest duration of pain and the largest pain area under the VAS-time curve (P<0.001) in both men and women, although responses in women were larger than in men (P<0.05). The face-chart pain area was the largest for the highest concentration of glutamate (P<0.001) and women drew a larger pain area than men (P=0.024). The area of pinprick hyperalgesia was the largest for glutamate 100mM (P<0.001) and women indicated a larger area than men (P<0.001). Concentration-dependent local vasomotor responses were found following the subcutaneous injection of glutamate but there was no sex difference in this effect. Glutamate 100mM significantly reduced the PPT values (P<0.001) without sex-related differences. The present study demonstrates for the first time that subcutaneous injection of glutamate evokes pain, vasomotor responses and pinprick hyperalgesia in human volunteers and that there are sex-related differences in some of these responses.     

Catastrophizing as a mediator of sex differences in pain: differential effects for daily pain versus laboratory-induced pain

Sex differences in the experience of pain have been widely reported, with females generally reporting more frequent clinical pain and demonstrating greater pain sensitivity. However, the mechanisms underpinning such differences, while subject to intense speculation, are not well-characterized. Catastrophizing is a cognitive and affective process that relates strongly to enhanced reports of pain and that varies as a function of sex. It is thus a prime candidate to explain sex differences; indeed, several prior studies offer evidence that controlling for catastrophizing eliminates the gap between men and women in reported pain. We recruited 198 healthy young adults (115 female) who took part in laboratory studies of pain responses, including thermal pain, cold pain, and ischemic pain, and who also completed questionnaires assessing catastrophizing, mood, and day-to-day painful symptoms (e.g. headache, backache). Women reported greater levels of catastrophizing, more recent painful symptoms, and demonstrated lower pain thresholds and tolerances for noxious heat and cold relative to men. Mediational analyses suggested that after controlling for negative mood, catastrophizing mediated the sex difference in recent daily pain but did not mediate the much larger sex differences in pain threshold and tolerance. These findings highlight the role of catastrophizing in shaping pain responses, as well as illuminating potentially important differences between experimental pain assessment and the clinical experience of pain.     

An evaluation of sex differences in psychological and physiological responses to experimentally-induced pain: a path analytic description

A cold pressor task (CPT) was used with 203 college students (112 women and 91 men) in a study of sex differences in pain response. Physiological measures were taken before and after pain induction, and sex-differentiating personality traits were assessed with the Personal Attributes Questionnaire (PAQ). The Pain Catastrophizing Scale (PCS) was given with standard instructions prior to the CPT, and it was re-administered after the CPT with modified instructions to assess catastrophic thinking during the CPT. Hypotheses were formulated into an explanatory model that was evaluated by path analysis. Pain induction elevated blood pressures and cortisol levels for both sexes, but systolic blood pressure reactivity and cortisol response were greater in men, even with sex differences in CPT tolerance times controlled statistically. Post-CPT PCS scores were positively related to pain ratings and negatively related to tolerance, but baseline PCS scores did not predict tolerance or pain ratings. Pre-PCS scores were not well correlated with post-PCS scores (r=0.46) and underestimated post-PCS scores, particularly for women. The Sex difference on the post-CPT PCS was largely attributable to the PAQ personality trait of Emotional Vulnerability. The differential results obtained from assessing catastrophizing before and after the CPT emphasized the importance of specifying the context in which catastrophizing is assessed (both timing and instructions). Theoretical considerations in the construct of catastrophizing are also highlighted, including, but not limited to, the confounding of variables such as pain intensity and unpleasantness.     

Noxious heat evokes stronger sharp and annoying sensations in women than men in hairy skin but not in glabrous skin

Brief noxious heat evokes more intense pain in women than in men; however, sex differences in the intensity of pain sensations evoked in hairy and glabrous skins are not clearly understood. Glabrous skin putatively lacks the type of A-delta nociceptors that underlie heat-evoked sharp sensation. Therefore, we assessed whether noxious heat-evoked pain qualities differed for hairy and glabrous skins and whether sex differences exist in these evoked pains. We applied a prolonged (30 s) ramped noxious heat stimulus to the dorsal and ventral aspects of the feet of 16 males and 16 females. Stimuli were calibrated in each subject to evoke a peak pain magnitude of 50/100. Subjects provided continuous online ratings of pain, annoyance, burning, sharp, stinging and cutting sensations in separate runs. The results indicate that both sex and skin type impact noxious heat-evoked sensations. Specifically, ratings of sharp sensations and annoyance evoked in hairy skin were significantly more intense in women than in men. Sharp, stinging and cutting sensations were evoked in glabrous skin, but the magnitude of these sensations was greater in hairy skin than glabrous skin; an effect only in females. Also, there was no sex difference in sharp sensation and annoyance in glabrous skin. These findings suggest that sharp sensations are evoked more prominently in hairy than in glabrous skin of women and that sharp sensations and annoyance play a prominent role in mediating aspects of pain-evoked from hairy skin in women.     

A comparison of diffuse noxious inhibitory controls in men and women.

Results from clinical and experimental pain studies provide consistent evidence of sex differences in pain perception, with women reporting more clinical pain and demonstrating lower pain threshold and tolerance levels than men. The present study was designed to assess the notion that sex differences in pain perception may be related to differential activation of supraspinal pain modulation systems. Specifically, the phenomenon of diffuse noxious inhibitory controls (DNIC) was examined in healthy young adult men (n = 39) and women (n = 44) using repeated assessment of nociceptive flexion reflex activity before, during and after exposure to forearm ischemia. Consistent with previous research, women exhibited significantly lower nociceptive flexion reflex thresholds than men, and reported significantly greater pain in response to both forearm ischemia and repeated electrocutaneous stimulation required to elicit the nociceptive flexion reflex. Application of forearm ischemia was associated with a significant decrease in nociceptive flexion reflex activity in both men and women, however, the degree of attenuation of nociceptive flexion reflex activity was not significantly different between the sexes. These findings suggest that men and women exhibit similar activation of diffuse noxious inhibitory controls, but they do not exclude the possibility of sex differences in other forms of central pain modulation.     

Gender, interpersonal transactions, and the perception of pain: an experimental analysis.

Two experiments assessed how interpersonal transactions influence responses to cold pressor pain in women versus men. In Experiment 1, 91 young adults (57 women, 34 men) were randomly assigned to either a no transaction (NT) condition in which they coped alone with the cold pressor test or a transaction opportunity (TO) condition in which they also had the option of interacting with an empathetic, reflecting experimenter. Compared to men, women had lower pain tolerance and reported more pain and catastrophizing, although there were no gender differences in support seeking or other ways of coping. Within the TO condition, women were no more likely than men to initiate a transaction, but female speakers were more pain-focused than male speakers, and speaking with the empathetic interaction partner had generally negative effects on pain perception and coping. In Experiment 2, 126 young adults (76 women, 50 men) were randomly assigned to NT, TO, or experimenter-directed (1) Distraction (DT), (2) Reinterpretation (RT), or (3) Encouragement (ET) conditions. Although men had similar levels of pain tolerance across the 5 transaction conditions, women in NT and TO conditions exhibited reduced tolerance compared with those in the DT, RT, and ET conditions. Pain tolerance times among women in DT, RT, and ET conditions were equal to or exceeded those of men in these conditions. Together, findings suggest the nature of interpersonal transactions exerts a greater influence on women's responses to noxious stimulation than those of men. PERSPECTIVE: This study adds to literature indicating that women exhibit reduced tolerance for experimentally induced pain compared with men. These results suggest that the nature of interpersonal transactions also affects women's responses to noxious stimulation, more than those of men.     

Emotion‐focused coping and distraction: Sex differences in the influence of anxiety sensitivity during noxious heat stimulation

While previous research has indicated that the relative efficacy of attentional strategies on pain may be influenced by anxiety sensitivity (AS) and sex, no study appears to have examined this within the context of an emotion‐focus versus distraction paradigm. The present study compared the effect of attentional emotion‐focus and distraction instructions on pain response with noxious heat stimulation in 114 healthy adults (62 women and 52 men) varying in levels of AS. Results indicated that men reported a significantly higher mean tolerance time than women. Moderated regression analysis also revealed a significant strategy × anxiety sensitivity × sex interaction on pain tolerance. For those low in AS, relative efficacy was dependent upon sex, with distraction superior to emotion‐focusing in women, but with strategies equivalent in men. For those high in AS, however, distraction resulted in uniformly greater pain tolerance than attentional emotion‐focusing. These results indicate that AS and sex may be influential in determining the relative effectiveness of distraction and emotion‐based attentional strategies for pain management.     

Sex differences and hormonal influences on response to cold pressor pain in humans.

Although most studies show that women have higher subjective pain ratings in response to painful stimuli, there is less consistency across studies with regard to the influence of gonadal hormones on pain responsivity. The present study evaluated sex differences in response to cold pressor pain in normally menstruating women (NMW), women maintained on oral contraceptives (OCW), and men. Testing occurred during 5 phases of the menstrual cycle. All participants completed 10 sessions (2 sessions per phase). During the cold pressor test, participants immersed the forearm into water maintained at 4 degrees C, and pain threshold and tolerance were measured. Subjective ratings of pain, physiologic indices, and plasma levels of estradiol and progesterone were also assessed. Both estradiol and progesterone levels varied as a function of menstrual cycle phase in NMW and were significantly higher in NMW compared with OCW and men. There were no significant differences in pain threshold or tolerance for any of the groups as a function of menstrual cycle phase. There were no significant differences in pain tolerance between groups. However, pain threshold was higher in NMW compared with OCW and men. When the data were reanalyzed across consecutive sessions, a significant sex-by-day interaction was observed for both threshold and tolerance. Specifically, pain threshold and tolerance were similar for NMW, OCW, and men, but these latencies changed at different rates across session days. Pain threshold remained relatively constant for both OCW and men, but it increased across days for NMW. Pain tolerance remained stable across sessions in OCW, a slow consistent increase was observed for men, whereas a sharper increase, followed by an asymptote, was observed for NMW. These results suggest that circulating gonadal hormones might mediate adaptation to cold pressor pain. PERSPECTIVE: The present study supports the notion that differences in pain perception between the sexes and among menstrual cycle phases are subtle. However, normally menstruating women exhibited an increase in pain tolerance and threshold over repeated stimulation, whereas men exhibited a shallow increase in pain threshold only, suggesting a sex difference in the adaptation to painful stimuli in men and women.     

Sex Differences in Facial Encoding of Pain

There is substantial evidence that men and women differ in their perception and experience of pain. However, research on sex differences in pain has mainly relied on self-report ratings, whereas little is known about sex differences in facial expression of pain. The aim of the present study was to investigate: 1) whether men and women differ in their facial expressiveness of pain; and 2) whether sex modulates the relationship between self-report and facial pain responses when tonic experimental pain is applied. Forty young and pain-free individuals (male n = 20, female n = 20) were investigated for their subjective and facial responses to tonic heat stimulation at both painful and nonpainful levels. Tonic heat stimulation was tailored to the individual pain threshold. Self-report was assessed via visual analog scales. Facial expression was objectively examined using the Facial Action Coding System. Correlation analyses for the relationship between self-report and facial expression of pain were conducted. Men and women differed neither in self-report ratings nor in facial responses during tonic heat stimulation. However, sex had a considerable impact on the relationship between these variables. Whereas no significant correlations at all were found for men, we obtained several significant correlations in woman. For that reason, future studies investigating the relationship between self-report and nonverbal pain behaviors should consider sex as an important modulating factor. PERSPECTIVE: The findings of the present study suggest that facial responses to pain can be used as estimates of the intensity of subjective pain in women better than in men.     

Sex differences in perceptual and cardiovascular responses to pain: the influence of a perceived ability manipulation

Sex differences in responses to experimental pain have been widely reported, with women typically showing lower pain threshold and tolerance than men. One possible explanation for these differences is that traditional gender roles may lead to sex differences in perceived ability to tolerate pain. To address this possibility, the present study evaluated the influence of a sex-related perceived ability manipulation on pain tolerance and cardiovascular responses to ischemic pain assessed via the submaximal effort tourniquet procedure. A sample of 68 young adults (35 women, 33 men) were randomly assigned to 1 of 2 perceived ability conditions, which depicted either women (FEM condition) or men (MASC condition) as more able to tolerate the painful task. The results indicated that men had higher pain tolerance than women. Although there was no overall effect of the experimental condition, only men in the FEM condition had higher tolerance than women. Also, men had greater blood pressure reactivity than women, and further analysis showed that women in the MASC condition had the lowest systolic blood pressure reactivity. Cardiovascular reactivity and motivation to tolerate the pain were positively correlated with pain tolerance only among men in the FEM condition. These findings indicate that the perceived ability manipulation produced only modest effects on pain tolerance and cardiovascular reactivity, but the relationship of cardiovascular and subjective responses to pain tolerance differed across conditions. These findings suggest that perceived ability may contribute to perceptual and cardiovascular responses to pain in a complex fashion, and further research to explicate these relationships is needed.     

Women experience greater heat pain adaptation and habituation than men

It is not clear how males and females cope with pain over time and how sensory and emotional qualities fluctuate from moment to moment, although studies of pain at discrete time points suggest that women are more pain sensitive than men. Therefore, we developed a new broader-based pain model that incorporates a temporally continuous assessment of multiple pain dimensions across sensory and affective dimensions, and normalized peak pain intensity to unmask sex differences that may otherwise be confounded by inter-individual variability in pain sensitivity. We obtained continuous ratings of pain, burning, sharp, stinging, cutting, and annoyance evoked by repeated prolonged noxious heat stimuli in 32 subjects. Strikingly, females reported more pain than males at the outset of the first exposure to pain, but then experienced less pain and annoyance than males as a painful stimulus was sustained and with repeated stimulation. Patterns of pain and annoyance attenuation in women resembled the attenuation of sharp, stinging and cutting sensations, whereas patterns of pain and annoyance in men resembled burning sensations. Taken together, these data demonstrate a prominent sex difference in the time course of pain. Notably only females demonstrate adaptation and habituation that allow them to experience less pain over time. These findings suggest a sexual dichotomy in mechanisms underlying pain intensity and annoyance that could involve specific quality-linked mechanisms. Importantly, temporal processing of pain differs between males and females when adjusted for sex differences in pain sensitivity. Our findings provide insight into sex differences in tonic and possibly chronic pains.     

Personality factors in the explanation of sex differences in pain catastrophizing and response to experimental pain

OBJECTIVE: To examine the effects of personality and pain catastrophizing upon pain tolerance and pain ratings and to examine the impact of an experimental pain induction on subsequent ratings of catastrophizing. METHOD: Two hundred nineteen college students participated in a cold pressor task. Sex-differentiating personality constructs were measured by the Extended Personal Attributes Questionnaire. The Pain Catastrophizing Scale was given before and after the cold pressor task. RESULTS: A path-analytic model fit the data well and permitted tests of explanatory relationships. Mediational analyses demonstrated that sex differences in catastrophizing were explained by the Personal Attributes Questionnaire Masculinity-Femininity and Verbal Passive-Aggressiveness scales. Pain tolerance and pain ratings differed significantly between men and women, but Masculinity-Femininity partially mediated those sex-pain relationships. Additionally, higher pain ratings and lower pain tolerance were independently associated with increased catastrophizing after the cold pressor task. CONCLUSIONS: The results suggest that sex differences in catastrophizing and pain responsivity are partially accounted for by the dispositional tendency to describe oneself as emotionally vulnerable. The findings also suggest that pain catastrophizing may be situational as well as dispositional.     

Sex differences in perceived pain are affected by an anxious brain

Decades of research confirm that women have greater pain sensitivity than men. Women also show greater overall anxiety sensitivity than men. Given these differences, we hypothesized that sex differences in anxiety would explain sex differences in experienced pain and physiological responses to pain (at both spinal and cortical levels). By measuring subjective pain, state/trait anxiety, nociceptive flexion reflexes, and somatosensory evoked potentials (SEPs), it was possible to test the effects of anxiety on the processing of painful drives at different levels of the neuraxis while also documenting the role played by anxiety on sex differences in experienced pain. Results confirm that women are indeed more sensitive to pain than men. Importantly, this difference was accompanied by a significant sex difference in cortical activity (SEP amplitude) but not spinal nociceptive activity, suggesting that much of the sex difference in experienced pain is attributable to variations in thalamocortical processing and to ensuing changes in the appraisal of and/or emotional response to noxious insult. In support of this claim, we found that sex differences in cortical activity and subjective pain disappeared when trait anxiety was controlled for. This means that stable predispositions to respond with heightened apprehension contribute to baseline pain sensitivity differences between the sexes. These results indicate that the modulatory effect of affect on pain-related brain processes may explain why men and women experience painful shocks so differently. In our study, the mediating role of anxiety on sex differences in pain was tested and confirmed using path analysis.     

Sex, gender, and pain: Women and men really are different

Sex-related differences in the experience of both clinical and experimentally induced pain have been widely reported. Specifically, females are at greater risk for developing several chronic pain disorders, and women exhibit greater sensitivity to noxious stimuli in the laboratory compared with men. Several mechanisms have been proposed to account for these sex differences. Psychosocial factors such as sex role beliefs, pain coping strategies, mood, and pain-related expectancies may underlie these effects. In addition, there is evidence that familial factors can alter pain responses, and these intergenerational influences may differ as a function of sex. Sex hormones are also known to affect pain responses, which may mediate the sex differences. Although the magnitude of these effects has not been well characterized, there are potentially important practical implications of sex differences in pain responses. These implications are discussed, and directions for future research are delineated.     

Gender bias in the observation of experimental pain

The aim of this study was to examine how men and women observe experimentally induced pain in male and female participants and to specifically determine the accuracy of observed pain ratings, the possible interactions between the sex of the viewer and the sex of the individual being observed, and the influence of gender role expectations on observed pain ratings. The sample comprised 29 participants (15 females). They each completed a battery of psychological questionnaires and viewed a presentation of 10 randomly ordered video clips. Each presentation consisted of 10 video clips, lasting 30s, of a participant (five males and five females) in the cold pressor task. The participants viewing the videos were asked to provide several ratings, including observed pain intensity and gender role related characteristics of the individual in the video. In terms of sex of the video participant, results indicated that viewers rated male videos as having less pain than female videos although the effect was small. Regarding sex of the viewer, results indicated that for both male and female videos, female viewers rated observed pain intensity significantly higher than did male viewers. In terms of accuracy, results indicated that on average, female video participants' pain was underestimated by 14 points, while male videos participants' pain was underestimated by 22 points (on a 0-100-point scale). Pain intensity ratings and pain tolerance from the participants in the videos did not differ significantly with respect to sex, though women had shorter tolerance times and higher pain ratings than men. Hierarchical regression analyses indicated that expectations of gender related 'endurance of pain' significantly predicted ratings of both male and female videos. When endurance expectations were controlled, sex of the viewer no longer significantly predicted observed pain ratings. The 'willingness to report pain' variable was not a significant predictor of observed pain ratings. Our results show that women are perceived to have more pain than men, that there was a tendency by both sexes to underestimate pain in others, but men showed even greater underestimation, and that gender role expectations of pain endurance given by the video observers accounted for substantial variance in their ratings of pain in the videos.     

Sex Differences in Prior Pain Experience

Sex differences in clinical and experimental pain experiences are well documented. However, there has been little work investigating men's and women's experiences with common painful events. This study examined sex differences in the nature and intensity of common pain experiences. Participants (102 women and 85 men) completed the Prior Pain Experience Questionnaire, which is a 79-item assessment of an individual's pain experience, recalled pain ratings, and imagined pain ratings. Analyses of variance were conducted to assess for sex differences in overall pain experience and pain ratings. Men and women did not have significant differences in the overall number of reported pain experiences or in the overall mean pain rating of those experiences. However, they differed in specific pain events experienced (eg, men experienced concussions more than women) and pain ratings (eg, women rated minor surgery as significantly more painful than men). Individuals who imagined pain events tended to rate them as equally or more painful than individuals who experienced those pain events.PerspectiveResults of this study demonstrate that men and women have varying types of pain experiences without evidence that the overall pain experience differs between sexes. It was also found that imagined pain ratings are often worse than experienced pain ratings, lending support for the tendency of individuals to catastrophize.     

Effects of temperature on heat pain adaptation and habituation in men and women

We recently reported that women report greater pain adaptation and habituation to moderately painful heat stimuli than men (Hashmi and Davis [16]); but slightly lower temperatures were needed to evoke moderate pain in the women. Hardy et al (1962) and LaMotte (1979) suggested that pain adaptation is most prominent at modest noxious heat temperatures and may occur at temperatures close to pain thresholds. Thus, as a follow-up to our previous study, we examined the role of absolute temperature in pain adaptation and habituation in men and women and assessed whether pain threshold impacts these findings. We hypothesised that pain adaptation and habituation would be more prominent at low and moderate temperatures, and that higher temperatures would induce pain adaptation and habituation in women but not in men. We further hypothesized that pain adaptation would not be correlated with pain thresholds. To test this, we obtained continuous ratings of pain evoked by 44.5-47.5°C stimuli applied to the dorsal foot of men and women. Each run consisted of three 30 s stimuli at the same temperature with a 60 s inter-stimulus interval. Women showed within-stimulus adaptation of total pain at all temperatures, but men showed significant adaptation to temperatures less than 47 °C. There were no sex differences in inter-stimulus habituation and both men and women reported habituation to temperatures less than 46 °C. Pain thresholds did not correlate with pain adaptation. These data highlight the temperature-sensitivity and sex differences of pain adaptation and habituation.