Grutsch et al. BMC Cancer 2011, 11:193 http://www.biomedcentral.com/1471-2407/11/193 Page 7 of 13 Table 4 Actigraphic sleep-activity characteristics of non-small cell lung cancer patients compared to normal individuals during the putative wakefulness and during the putative sleepfulness Parameters N Daytime Activity Mean Activity (accel/min) Wake Minutes Sleep Minutes % Sleep Duration of Longest Sleep (min) Nighttime Wake Minutes Sleep Minutes % Sleep Sleep Efficiency (%) Duration of Longest Sleep Sleep Latency (min) All patients 68 126.9 ± 4.9 797.5 ± 26 208.8 ± 18 20.9 ± 1.8 43.0 ± 2.8 95.0 ± 8.8 284.0 ± 18.3 72.5 ± 2.0 79.8 ± 1.7 91.7 ± 7.4 20.8 ± 2.5 Inpatients 35 111.7 ± 7.1 714.2 ± 36 241.3 ± 25 25.8 ± 2.8 45.4 ± 4.0 97.5 ± 12.2 300.5 ± 24.8 73.3 ± 2.6 80.8 ± 2.4 100.3 ± 11.8 18.1 ± 2.9 Outpatients 33 143.0 ± 5.6 885.8 ± 31 174.4 ± 24 15.6 ± 1.9 40.5 ± 3.9 92.3 ± 12.9 266.4 ± 27.2 71.6 ± 3.08 78.7 ± 2.5 82.5 ± 8.6 23.7 ± 4.0 Healthy Controls 35 182.6 ± 25 947.1 ± 11 46.5 ± 6.9 4.7 ± 0.7 23.6 ± 0.6 31.1 ± 3.6 417.89.4 93.0 ± 0.8 95.9 ± 0.7 225.6 ± 17 12.1 ± 6.9 *Inpatient vs. Outpatient difference is significant for all parameters (t-test, p < 0.05). significant positive relationship with 24-hour autocorrela- tion, or day-to-day circadian stability of peak and trough activity timings (r = 0.45, p = 0.02). Each Ferrans-Powers QLI domain exhibits a statistically significant relationship with the actigraphy parameter night-day sleep balance and quality of life scores in health/functioning (r = 0.39, p = 0.04), social/economic (r = 0.40, p < 0.04), psycholo- gical/spiritual (r = 0.45, p = 0.02), and family (r = 0.33, p = 0.10). The more robust the day/night difference between nocturnal and daytime activity levels, the better the patients score by each and every QLI measure. Relationships between EORTC QLC 30 and Actigraphy- measured Circadian Function Statistically significant correlations between EORTC QLQ C30 domains among outpatients were found. Glo- bal health exhibits a statistically significant positive asso- ciation with circadian phase stability as reflected by the 24-hour autocorrelation (r = 0.53, p < 0.01), (see figure 2). The actigraphy parameter, night-day balance of time spent asleep and awake, shows a statistically significant association with the EORTC QLQ C30 domains role (r = 0.56, p < 0.01) and cognitive function (r = 0.45, p = 0.02). Circadian Organization and EORTC Symptom Items Outpatient fatigue levels are associated with diminished robustness of the circadian quotient (r = -0.40, p = 0.04), rhythm quotient (r = -0.41, p = 0.03) and night- day balance of time spent asleep (r = -0.52, p < -.01). The more quantitatively robust the day-night activity/ sleep measurement differences, the less fatigue these patients experience during each day. Rhythm quotient is also inversely associated with pain (r = -0.39, p = 0.04). The greater the pain, the less robust were day-night activity differences, objectively verifying that pain inter- feres with both sleep at night and activity during each day. Loss of appetite is likewise associated negatively with the actigraphy parameters night-day sleep balance (r = -0.47, p < 0.01). The more disordered the circadian organization, the more profound the cancer-associated loss of appetite. Unlike the analysis for quality of life outcomes, there were no statistically significant associations found between actigraphy data and chronic COPD severity in this patient population with symptomatic advanced lung cancer. Relationships of Quality of Life Scores to one another and to Circadian Organization Figure 3 shows the relationships among two measures of quality of life and circadian organization parameters. A robust circadian rhythm in activity/rest is associated with greater patient satisfaction with health/functioning, less fatigue, and better overall quality of life. These rela- tionships, though present among all patients, are espe- cially clear among outpatients where hospitalization does not mask usual circadian time structure. Discussion Circadian organization optimizes organismal function at all levels of biological organization [4,39,40]. A faltering