2.4. Blood Samples and Assays
BLOOD, EMD
Blood samples were taken after arrival (at 20:00 h), after dinner at 21:00 h, and at 22:00 h. Blood samples were also collected during the night every two hours from 24:00 h to 06:00 h. If under sleep conditions, blood samples were collected via long line running from the participants’ arm to the adjacent room, allowing participants’ sleep not to be disturbed. Subsequent blood samples were taken in the morning at 07:00 h and, thereafter, at 09:00 h, 10:00 h, and 11:00 h until the end of the experiment. Leptin and total ghrelin concentrations were measured by radio-immunoassays (RIA Kit, EMD Millipore, St Saint Louis, MO, USA) with the following within and between assay variation: <8.3% and <6.2% for leptin (mean: 4.9 ng/mL); <10.0% and <14.7% for ghrelin (mean: 1000 pg/mL). All values were determined from stored (−80 °C) plasma samples.