Extra detail about the big sleep experiment
For one week participants were randomly scheduled to either 8 hours sleep or 6.5 hours sleep. Their sleep patterns were measured with Actiwatches which allowed us to check the number of hours that they were sleeping.
After the first week, a single blood sample was collected between 1pm and 3pm in Paxgene tubes for subsequent RNA extraction. During the second week, the same participants were scheduled to the opposite condition to the first week, and at the end of this second week another single blood sample for RNA was again extracted between 1pm and 3 pm. Seven participants completed both weeks of the study.
The RNA was extracted, copied and analysed for significant differences between conditions. Compared with one week of sufficient sleep, sleep restriction led to significant changes in the expression of 380 genes. Of these, 220 genes were down regulated by sleep restriction (ie their levels of expression were reduced), while 160 were up regulated (ie their levels were increased).
Genes affected included body clock genes (RORA and NPAS2, which is also linked with metabolism) and the body clock output gene DBP, which controls the expression of clock-controlled genes and is also linked with diabetes.
Other genes were associated with cell development and signalling pathways (eg WNT2B), immune responses (human leukocyte antigens, HLA genes), solute carriers (SLC genes linked with metabolic pathways), and the regulation of gene expression (ribosomal subunits and translation control factors).
One of the most down regulated genes was PAX6, which is a developmental homeobox gene that also has a role in the control of insulin secretion and is linked with diabetes and insomnia. The most up regulated gene was CKM (creatine kinase), which is linked with cardiovascular disease.
