Effect of sleep deprivation on cholesterol metabolism and triglyceridaemia in male volunteers.

The effect of 5-day sleep deprivation (SD) on cholesterol metabolism, together with triglyceridaemia, was studied in seven healthy male volunteers. A 3-day control period was followed by 5 days (120 h) complete SD and 4 days recovery. Blood was collected at 9 a.m. and at 9 p.m. Vastus lateralis muscle biopsy was performed during the control period, on the 5th day of SD, and on day 3 of recovery. The value of muscle cholesterol was related to the non-collagen protein content. The plasma triglycerides (TG) varied in a circadian biorhythm, the amplitude of which declined gradually during SD. The morning triglyceridaemia was significantly decreased on days 3-5 of SD (35%-79% of initial values). On days 4 and 5 of SD, plasma cholesterol fell significantly to 78% and 88% of control values, respectively. The ratio of its esterified to unesterified fractions remained unchanged throughout SD. Basal activity of lecithin cholesterol acyltransferase (LCAT) showed no diurnal biorhythm; on the last 2 days of SD, LCAT activity fell significantly to 71%-80%. In contrast, the decrease in fractional esterification rate (FER) was insignificant. In the vastus lateralis muscle, total cholesterol (TC) was decreased by 40% at the end of SD, the reduction being greater for cholesterol esters (CE) (by 63%) than for free cholesterol (FC) (by 36%). The relative proportion of CE significantly decreased from an initial 14.7% to 9.2% on the last day of SD. During recovery after SD, plasma cholesterol and TG slowly returned to normal. LCAT activity and FER recovered quickly, within 48 h.(ABSTRACT TRUNCATED AT 250 WORDS)