Mean mRNA levels of GABAA receptor subunits, GABA-synthesizing enzymes GAD65 and 67, and prepro-orexin (ORX) in relation to sleep need and circadian time in the posterior hypothalamic perifornical (PF) and dorsomedial (DM) regions.

a– mRNA levels are expressed as copy numbers per 1 ng of total RNA in tissue sample ± standard error; AM – significantly different from the 9 AM group; SD – significantly different from the 3–4 PM group subjected to sleep deprivation (SD) prior to tissue extraction; numbers in parentheses indicate the numbers of animals used to obtain tissue samples under each condition. See Methods for the criteria used to categorize the effects as either sleep need- or circadian time-dependent.