HCRT and narcolepsy: In two of them, nocturnal BP dipping was absent or blunted in patients with narcolepsy, compared to a control group of healthy subjects.[19,20] In the third study, non-dipping was shown to occur equally in a small group of narcoleptic and insomnia patients, suggesting that sleep disturbance, rather than an absence of orexin, diminishes BP dipping.[21]