The ability to achieve sufficient restorative sleep is important in the maintenance of physical and mental health; however, disturbed sleep and insomnia symptoms are a common experience among women with breast cancer. In non-cancer populations, insufficient sleep quantity and quality has been associated with shortened telomere length (TL), a measure of accumulated cellular damage and human aging. This feasibility study compared TL in women previously diagnosed with breast cancer with clinically significant insomnia symptoms (n=70) to an age- and body mass index (BMI)-matched comparison group (n=70) of breast cancer survivors. Women with significant insomnia symptoms had higher levels of unemployment compared to women without insomnia. TL was positively skewed and shorter in the insomnia group (Median=6.000, S=1.000, standard error [SE]=0.287) than the control group (Median=6.195, S=-0.269, SE=0.287); however, this was not significant (p=0.29). Women with insomnia also reported significantly higher levels of depression (p<0.001), anxiety (p<0.001), and fatigue (p<0.001). This study provides the first measure of effect size and variability of TL in women with breast cancer and highlights the need for larger sample sizes to investigate the impact of insomnia and co-morbid symptom distress on cellular aging.