Seasonal influence over serum and urine metabolic markers in submariners during prolonged patrols.

Within the framework of earlier publications, we have consistently dedicated our investigations to eliciting the effects of both seasonal vitamin D deficiency and submarine-induced hypercapnia on serum parameters for acid-base balance and bone metabolism in submariners over a 2-month winter (WP) or summer (SP) patrols. The latest findings reported herein, contribute further evidence with regard to overall physiological regulations in the same submariner populations that underwent past scrutiny. Hence, urine and blood samples were collected in WP and SP submariners at control prepatrol time as well as on submarine patrol days 20, 41, and 58.

Effects of 29-h total sleep deprivation on local cold tolerance in humans.

To study the effects of a 29-h total sleep deprivation (TSD) on local cold tolerance, 10 healthy men immersed their right hand for 30 min in a 5°C water bath (CWI) after a 30-min rest period in a thermoneutral environment (Control), after a normal night (NN) and after a 29-h TSD. CWI was followed by a 30-min passive rewarming (Recovery). Finger 2 and 4 skin temperatures (Tfi2, Tfi4) and finger 2 cutaneous vascular conductance (CVC) were monitored to study cold-induced vasodilation (CIVD).

Cold adaptations.

Nowdays, occupational and recreational activities in cold environments are common. Exposure to cold induces thermoregulatory responses like changes of behaviour and physiological adjustments to maintain thermal balance either by increasing metabolic heat production by shivering and/or by decreasing heat losses consecutive to peripheral cutaneous vasoconstriction. Those physiological responses present a great variability among individuals and depend mainly on biometrical characteristics, age, and general cold adaptation.

Zaleplon and zolpidem objectively alleviate sleep disturbances in mountaineers at a 3,613 meter altitude.

Study Objectives: To assess the effects of zolpidem and zaleplon on nocturnal sleep and breathing patterns at altitude, as well as on daytime attention, fatigue, and sleepiness.

Design: Double-blind, randomized, placebo-controlled, cross-over trial.

Setting: 3 day and night alpine expedition at 3,613 m altitude.