Abstract
Orthostatic intolerance (OI) is a major problem following spaceflight, and, during flight, astronauts also experience sleep restriction. We hypothesized that sleep restriction will compound the risk and severity of OI following simulated microgravity and exaggerate the renal, cardioendocrine, and cardiovascular adaptive responses to it. Nineteen healthy men were equilibrated on a constant diet, after which they underwent a tilt-stand test. They then completed 14-16 days of simulated microgravity [head-down tilt bed rest (HDTB)], followed by repeat tilt-stand test. During HDTB, 11 subjects were assigned to an 8-h sleep protocol (non-sleep restricted), and 8 were assigned to a sleep-restricted protocol with 6 h of sleep per night. During various phases, the following were performed: 24-h urine collections, hormonal measurements, and cardiovascular system identification. Development of presyncope or syncope defined OI. There was a significant decrease in time free of OI (P = 0.02) and an increase in OI occurrence (P = 0.06) after HDTB among all subjects. However, the increase in OI occurrence did not differ significantly between the two groups (P = 0.60). The two groups also experienced similar physiological changes with HDTB (ini...Continue Reading
References
Aug 1, 1992·Journal of Applied Physiology·J M FritschD L Eckberg
Feb 1, 1991·Medicine and Science in Sports and Exercise·H I Chen
May 1, 1991·British Heart Journal·D J EwingW Reid
Nov 1, 1989·IEEE Transactions on Bio-medical Engineering·R D BergerR J Cohen
Mar 1, 1995·Journal of Applied Physiology·D S GoldsteinV A Convertino
Oct 1, 1994·Journal of Applied Physiology·J M Fritsch-YelleD L Eckberg
Jan 1, 1994·Journal of Clinical Epidemiology·D L BliwiseR B Harris
May 1, 1996·American Journal of Hypertension·P LusardiR Fogari
Jul 1, 1996·Journal of Applied Physiology·C S LeachJ M Krauhs
Nov 1, 1996·Journal of Applied Physiology·J M Fritsch-YelleT E Brown
Jan 1, 1997·The American Journal of Physiology·T J MullenR J Cohen
Mar 1, 1997·Journal of Sleep Research·A GundelJ Zulley
Mar 10, 1999·The American Journal of Physiology·R MukkamalaR Freeman
Jun 9, 1999·Scandinavian Journal of Work, Environment & Health·H Bøggild, A Knutsson
Sep 1, 1999·Clinical Endocrinology·A N VgontzasG P Chrousos
Oct 30, 1999·Lancet·K SpiegelE Van Cauter
Mar 10, 2000·Journal of Applied Physiology·N K MuenterM L Smith
May 20, 2000·Hypertension·M KatoV K Somers
Jul 25, 2000·Journal of Applied Physiology·N D VaziriR E Purdy
Aug 24, 2000·Journal of Applied Physiology·W H CookeD L Eckberg
Apr 11, 2001·Circulation·M A PerhonenB D Levine
Jul 18, 2001·Journal of Applied Physiology·M A PerhonenB D Levine
Oct 20, 2001·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·D J DijkC A Czeisler
Nov 24, 2001·Psychosomatic Medicine·J V MeckM G Ziegler
Mar 21, 2002·Journal of Internal Medicine·P M NilssonG Berglund
Sep 30, 2003·Journal of Applied Physiology·Xinshu XiaoRichard J Cohen
Feb 21, 2004·Journal of the American College of Cardiology·Hans K Meier-EwertJanet M Mullington
Apr 8, 2004·Journal of Investigative Medicine : the Official Publication of the American Federation for Clinical Research·S Marlene GrenonGordon H Williams
Apr 13, 2004·Journal of Applied Physiology·S M GrenonG H Williams