Stability and Amplitude of Diurnal Rest-Activity Highly Variable Among Patients With PTSD and Insomnia

The researchers used actigraphy sleep metrics to quantify diurnal rhythms via interdaily stability, intradaily variability, relative amplitude, and sleep regularity.

Individuals with posttraumatic stress disorder (PTSD) and insomnia varied significantly for diurnal rest-activity stability and amplitude compared with healthy controls. These findings were published in the Journal of Biological Rhythms.

United States military veterans (n=44) with PTSD and insomnia comorbidities, patients with insomnia (n=21), and healthy controls (n=33) from Project NITES (NCT01009112) were assessed for rest-activity by wearing a Respironics Actiwatch 2 on their non-dominant wrist for 1 week and by the diurnal sleep regularity (SRI), Insomnia Severity index (ISI), and Pittsburgh Sleep Quality Index (PSQI) instruments.

The PTSD, insomnia, and control cohorts differed significantly by age (mean, 35.53 vs 31.76 vs 30.88 years; P =.047), gender (male: 84.1% vs 57.1% vs 63.6%; P =.04), and educational attainment (less than college: 79.5% vs 42.9% vs 21.2%; P <.001), respectively.

The 2 patient cohorts did not differ significantly for diurnal rest-activity relative amplitude (P =.08), least active 5 hours (P =.11), SRI (P =.46), or interdaily stability (P =.84). The patients with PTSD, however, had greater inter-individual variability in least active 5 hours (P <.001), amplitude (P =.002), and stability (P =.03) compared with the patients with insomnia.

The patients compared with the healthy controls differed significantly for diurnal rest-activity relative amplitude (t, 10.76; P <.001), least active 5 hours (t, 8.03; P <.001), SRI (t, 14.25; P <.001), and interdaily stability (t, 8.55; P <.001) but not for intradaily variability (t, 0.63; P =.68) or most active 10 hours (t, 0.88; P =.50).

Among the individual patient groups, the differences remained significant between PTSD or insomnia cohorts compared with controls.

Total sleep time was observed to be correlated with least active 5 hours (r, -0.56; P <.001), relative amplitude (r, 0.55; P <.001), and most active 10 hours (r, -0.34; P <.05). Sleep efficiency was correlated with least active 5 hours (r, -0.53; P <.001) and relative amplitude (r, 0.44; P <.001). No rest-activity indexes correlated with PSQI or ISI scores.

This study may have been limited by its low sample sizes and the lack of control for occupation, which may have significantly impacted the diurnal activities during workdays.

These data indicated patients with PTSD and comorbid insomnia had greater fluctuations of diurnal rest-activity compared against patients with insomnia alone. Patients with PTSD may present with more heterogenous phenotypes. Diurnal rest-activity had little correlation with sleep estimates, indicating that these were distinct constructs.


Mascaro L, Phillips AJK, Clark JW, Straus LD, Drummond SPA. Diurnal rhythm robustness in individuals with PTSD and insomnia and the association with sleep. J Biol Rhythms. Published online January 20, 2021. doi:10.1177/0748730420984563.