Research indicates among all the anxiety disorders, generalized anxiety disorder (GAD) has the highest comorbidity rate with insomnia (i.e., they occur together). Studies with post- traumatic stress disorder (PTSD), on the other hand, reveal a different pattern.
SLEEP DISTURBANCES WORSENS PTSD
Notably, there is growing evidence that sleep difficulties may contribute to the development of post-traumatic stress disorder (PTSD). For example, a study reveals that a large majority of individuals who exhibit sleep problems within one month of a trauma do develop PTSD. Likewise, when sleep disturbance is successfully treated, PTSD symptoms also improve.
This interaction between sleep disturbance and the course of PTSD is more striking when we look at how insomnia affect the course of other anxiety disorders. Specifically, reports from a longitudinal naturalistic study (i.e., observation without interference) reveal that the presence of sleep disturbance at the beginning of the study did not predict the course of generalized anxiety disorder (GAD), social phobia, panic disorder (PD), or obsessive compulsive disorder (OCD) during the 5-year follow-up, suggesting that whether or not the sleep disturbance was successfully treated did not affect the course of any of those anxiety disorders.
By contrast, sleep disturbance did predict the course of PTSD, thus implying that PTSD sufferers were less likely to improve within 5 years if sleep disturbance was not resolved. More concerning is the finding suggesting that difficulties with sleep could even worsen the course of PTSD, exacerbating the symptoms and lengthening the course of the disorder. In conclusion, sleep disturbance has prognostic significance in relation to PTSD and therefore should be identified early on.
Reference:
Marcks, B.A., Weisberg, R.B., Edelen, M.O., & Keller, M.B. (2010). The relationship between sleep disturbance and the course of anxiety disorders in primary care patient. Psychiatry Research 17, 487-492.