Comparison of Postoperative Pain and Sleep Quality Based on Timing of Surgery: An Observational Study

INTRODUCTION

The circadian rhythm, intricately linked to the human sleep-wake cycle, is a biological mechanism developed by the body to adapt to its surroundings.^[1] A circadian rhythmicity must be expressed regularly for the body to sustain homeostasis.^[2] A naturally occurring resting state called sleep is marked by a reduced metabolism, a partial or complete loss of awareness, a reduction in or absence of voluntary muscular contraction, and an energy-preserving state.^[3] Sleep quality disturbance is usually influenced by various endogenous factors (such as delirium, depression, and anxiety) and exogenous factors (such as ambient noise in the surroundings and frequent staff interventions).^[4] In addition, post-surgically, patients are more likely to experience changes in their sleep patterns, sleep quality, and development of postoperative sleep disturbances (POSD). POSD is marked by an increase in the frequency of sleep awakenings, a decrease in rapid eye movement sleep, and a decrease in total sleep duration.^[1] It exacerbates postoperative pain and fatigue, increases the risk of postoperative delirium, and causes cardiovascular adverse events.^[5] Similarly, anaesthesia is another crucial aspect that can alter the quality of sleep, regardless of whether the anaesthesia is general or spinal.^[6] Anaesthetics can disrupt circadian rhythms via activation of N-methyl-D-aspartate (NMDA) and gamma-aminobutyric acid (GABA) receptors in the suprachiasmatic nucleus neurons, which influences clock gene expression and internal clock entrainment.^[7] Anaesthesia and surgery are also believed to impact the postoperative melatonin level, causing impairment of the sleep-wake cycle.^[8] In addition to postoperative sleep quality, pain management is also a crucial factor for surgical patients. Ineffective pain management could lead to certain physiological and pathological issues that ultimately hinder the recovery of the patients.^[9] Pain perception exacerbates poor sleep quality, creating a vicious circle in which pain impacts sleep quality and poor sleep quality amplifies perception of pain.[2]

Apart from the surgery and anaesthesia, the timing of the procedure is also thought to affect patients’ sleep quality and recovery.^[8] However, the influence of the timing of surgery on postoperative pain and sleep quality remains uncertain. Therefore, to better understand POSD, this study set out to investigate how surgical timing influences postoperative pain and sleep quality.

MATERIAL AND METHODS

RESULTS

Among 50 participants involved in the study, 34 (68%) underwent surgeries in the morning and 16 (32%) in the afternoon. The participants’ mean age was 49.30 ± 17.02 years, with a distribution of 26% aged 20-40 years, 38% aged 41-60 years, and 36% aged 61-80 years. The average Body Mass Index (BMI) was 23.3 ± 2.76, with the majority (74%) falling within the normal BMI range and 26% classified as overweight. Sex distribution revealed that the majority (70%) of participants were males. In terms of hospitalization, the majority (86%) of patients had a stay of 0-20 days, with 8% staying 21-40 days and 6% requiring 41-60 days, with a median length of stay of 10 days (7, 15). Antibiotic prophylaxis was predominantly administered using cefuroxime (82%), with other antibiotics such as ceftriaxone sulbactam (6%), meropenem (4%), cefoperazone sulbactam (2%), ciprofloxacin (2%), clindamycin (2%), and piperacillin tazobactam (2%) also utilized to varying degrees. Anaesthesia methods varied significantly, with spinal anaesthesia (94%) being the primary choice, particularly in morning surgeries (68%). Comparative analysis between morning and afternoon surgeries highlighted distinct clinical differences. Among the morning surgery group, all the surgeries were performed with spinal anaesthesia, and the afternoon surgeries were performed with spinal anaesthesia among 13 (81.2%). The average estimated blood loss among the morning surgery group was 95.29 ± 44.99 mL, and afternoon surgeries were 92.5 ± 37.85 mL. The average length of the surgery among morning surgeries was 2 ± 1.06 h, and afternoon surgeries were 4.6 ± 1.79 h. The details have been summarized in Table 1.

Overall, the POSD was observed in 29 (58%) of the study participants. The incidence of POSD among the morning group was 16 (44.44%), and in the afternoon group it was 10 (62.5%).

Sleep quality and pain levels were assessed at preoperative, POD 1, and POD 2, using the ISI and VAS, respectively. The mean ISI score increased from 8.34 pre-operatively to 9.82 on POD 1, indicating worsened sleep quality immediately after surgery, followed by an improvement to 5.58 by POD 2. Similarly, VAS pain scores decreased progressively from 7.18 pre-operatively to 3.58 by POD 2, reflecting a decline in perceived pain levels post-surgery. The details are summarized in Table 2.

The test of within subjects were carried out to determine the mean difference across three different time points (i.e., Preoperative, POD 1, and POD 2). Since the data violated the assumption of sphericity, the greenhouse gases was considered in the test. It revealed that the sleep quality was statistically significantly different [F = 90.438, effect size = 0.649, p <0.05]. Similarly, the pain scores also varied statistically significantly differently [F = 156.814, effect size = 0.762, p <0.001]. The details are summarized in Table 3.

Table 4 summarizes the mean values of sleep quality and pain based on the timing of surgery at three different time points. The mean preoperative sleep quality in the morning surgery group (7.56 ± 4.07) and in the afternoon surgery group (7.88 ± 5.60) did not differ significantly (p = 0.126). During POD 1, the morning surgery (8.01 ± 4.29) group had a mean score slightly lower compared to the afternoon group (9.56 ± 5.98), and it was statistically significant (p = 0.043). However, on POD 2, the afternoon group (5.85 ± 3.38) had a slightly higher mean compared to the morning group (5.00 ± 4.78). Similarly, on POD 1, the afternoon group (6.38 ± 2.24) had higher pain scores compared to the morning group (5.50 ± 1.5), it was not statistically significant (p = 0.109).

Further, insights into the relationships between various parameters and postoperative sleep quality were determined through the correlation coefficients and corresponding p values. The parameters like preoperative sleep quality [r = 0.830, p <0.001], preoperative pain scores [r = 0.473, p <0.001], and postoperative pain scores [r = 0.347, p = 0.014] were positively correlated and found to be statistically significant. However, age [r = 0.0.31, p = 0.830], BMI [r = -0.073, p = 0.616] and LOHS [r = 0.023, p = 0.874] was not significantly correlated. The details have been summarized in Table 5.

DISCUSSION

Healthy individuals require adequate sleep to preserve their physical and mental health. However, the incidence of POSD following major surgeries is quite high. Postoperative sleep problems may have a substantial impact on patients’ neurocognitive function and perhaps worsen the outcomes of patients. Anaesthesia, along with the prevalent use of opioids during general anaesthesia, is considered a contributing factor to POSD. Also, the surgery timing is known to alter the postoperative sleep quality.^[8] Thus, we investigated how patients undergoing lower limb surgery would perform in terms of postoperative sleep quality based on whether the surgeries were performed in the morning or the afternoon. According to our research, patients who had surgery in the morning had much higher quality postoperative sleep than patients who had procedures in the afternoon. A previously published study by Hou et al. studied the effect of morning and afternoon surgeries on sleep quality. It revealed that afternoon surgeries had a more serious effect on sleep function.^[12] In contrast, a study by Yang et al. observed a better short-term sleep quality in the afternoon group compared to those in the morning. However, the disparity was justified by the short-term variation in melatonin levels following surgery.^[8] A randomized controlled trial by Song et al. where surgeries performed in the afternoon had a higher degree of postoperative sleep disorders compared to surgeries in the night.^[13] In addition, different from our study, their study assessed the postoperative sleep quality among the morning (8.00-12.00) and night group (18.00-22.00). Our study also found that the mean preoperative ISI score was 8.34 ± 4.55. It was contradicting to the results by Yang et al., where the mean ISI score was 11.5 ± 5.6.^[14] The postoperative mean ISI score was 9.82 ± 4.84, which contradicted with the study by Wang et al., where the mean ISI score was 15.6 (range 2-25).[15]

POSD, a common postoperative brain dysfunction, was identified in 58% of our study participants, mirroring findings from Seid and Fenta, who reported poor sleep quality in 64.9% of their participants.^[4] A study conducted in China and Malaysia had also observed a poor sleep quality among 65.4% and 67.3% of participants, respectively.^[16,17] Notably, the afternoon surgery group showed a greater prevalence of POSD compared to the morning group (62.5% vs. 44.4%), aligning with the results of Hou et al., who similarly observed a higher occurrence of POSD in the afternoon group (70% vs. 37.9%), suggesting that afternoon surgeries may not promote early postoperative sleep recovery as effectively as morning surgeries.^[12] In addition, opioids have also been shown to affect the sleep quality of patients.^[18] Hence, the afternoon group were having higher impact on sleep quality. The postoperative pain scores were 5.78 ± 1.79, which gradually reduced to 3.58 ± 1.69 on POD 2. A similar pattern was observed in a study conducted among patients undergoing total joint arthroplasty by Luo et al., where the score was 4.99 ± 1.73 and reduced to 3.93 ± 1.54 on POD 3.^[19] However, the timing of surgery did not have any significant impact on the postoperative pain scores.

The correlation analysis revealed that the postoperative sleep quality scores increase as age increases, but this was not statistically significant. It was in contradiction to the study results of Chung et al., where higher age was statistically associated with lower sleep efficiency after surgery.^[20] In addition, LOHS increased the postoperative sleep quality scores, indicating a decreased postoperative sleep quality. It was correlating with the meta-analysis by Butris et al., where the poor postoperative sleep quality has increased length of stay.^[21] A study by Yu et al. discovered that individuals with preoperative sleep problems had an affected sleep awakening in the postoperative period, which was similar to our study results, where the preoperative sleep quality scores were positively correlated with postoperative sleep scores.^[22] More importantly, postoperative pain and circadian rhythm interact in a bidirectional manner. Poor surgical pain management can lead to postoperative disturbances in sleep. Similarly, our study found a positive correlation between postoperative pain and sleep quality scores. It indicated a link to poor sleep quality, heightened pressure pain sensitivity, and reduced intrinsic pain inhibition capacity. However, Cronin et al. study found the presence of sleep disturbances despite having well-controlled pain.[23]

However, the study results should be seen with certain limitations. The study did a comparison of sleep quality among morning and afternoon groups and did not take into consideration the other groups, like the night surgery group. In addition, the study did not use polysomnography, a gold standard for evaluating sleep function. The study’s results may not be generalizable as it was single centred study. The data on the sleep quality was assessed for short term after the surgery. As a result, the effect of having surgery at different times on long-term sleep quality has to be researched further. In addition to the surgery, certain factors like noise and light might have a negative effect on the postoperative sleep quality in the study, which were not assessed.

CONCLUSION

In conclusion, patients undergoing surgeries in the afternoon had a significantly higher impact on the postoperative sleep quality compared to the morning group. The timing of surgery did not have a significant impact on postoperative pain. However, the poor postoperative pain management was associated with poor postoperative sleep quality. Therefore, among high-risk individuals who are prone to developing POSD, consideration should be given to the timing of the surgery.