The influence of partial sleep deprivation during the second half of the night on
the secretion of thyroid stimulating hormone (TSH), thyroxin (T4), free T4 (fT4),
triiodothyronine (T3), prolactin (PRL), growth hormone (GH), luteinizing hormone (LH),
follicle stimulating hormone (FSH), and estradiol (E2) was investigated in 10 healthy
young women. Blood samples were drawn at hourly intervals over a 64-hour period (i.e.,
3 consecutive days and nights). During night 2, all subjects were awakened at 1:30
a.m. During partial sleep deprivation, TSH concentrations increased significantly
and remained elevated throughout the following day. Levels of T4, fT4, and T3 were
enhanced during the partial sleep deprivation hours only, and changes in these hormones
seemed to be independent of TSH. PRL levels decreased, LH and E2 concentrations increased,
and GH and FSH secretion remained unchanged during partial sleep deprivation. This
pattern of change of different endocrine axes during partial sleep deprivation resembles
those seen after total sleep deprivation, suggesting that similar neurochemical changes
are induced by both forms of antidepressant therapy. The late evening GH peak occurred
almost exclusively before the onset of sleep. Partial sleep deprivation did not influence
the chronobiological profiles of any of the hormones investigated. The chemical changes
underlying these alterations are speculated to involve enhancement of central norepinephrine
and dopamine activity with a concomitant increase in the activity of the sympathetic
nervous system.