A yoked control study used sleep recordings from 10 insomniacs to produce similar sleep patterns in a group of matched normal sleepers for 7 nights to determine if specific electroencephalographic (EEG) sleep patterns were responsible for the secondary insomnia symptoms reported by the insomniacs. Specifically, it was found that insomniacs display increased tension/confusion, decreased vigor, personality disturbance, subjective over-estimation of poor sleep, increased body temperature, increased 24-hour whole body metabolic rate, and increased multiple sleep latency test (MSLT) values. Normal sleepers given the nocturnal EEG parameters of insomniacs displayed decreased tension, decreased vigor, decreased body temperature, and decreased MSLT values. The spectrum of changes seen in the normal sleepers given an insomniac sleep pattern was characteristic of mild partial sleep deprivation and not consistent with symptoms found in patients with primary insomnia. It was concluded that the secondary symptoms reported by patients with primary insomnia are probably not related to their poor sleep per se. Data from previous studies that varied physiological arousal were used to support the contention that the secondary symptoms of insomnia, including poor sleep, occur secondary to central nervous system hyperarousal.