Heat tolerance after total and partial acute sleep deprivation

Area of Science:

• Physiology
• Sleep Science
• Environmental Health

Background:

• Sleep deprivation (SD) is hypothesized to impair thermoregulatory functions.
• Understanding the impact of varying sleep loss on physiological responses to heat is crucial for public health and performance.

Purpose of the Study:

• To quantify the effects of partial sleep deprivation (PSD) and total sleep deprivation (TSD) on thermoregulation during a heat tolerance test (HTT).
• To investigate the influence of chronotype on thermoregulatory responses following sleep deprivation.

Main Methods:

• Eleven healthy participants completed a standard heat tolerance test (HTT) under three conditions: well-rested, after 24-hour partial sleep deprivation (PSD), and after 24-hour total sleep deprivation (TSD).
• Physiological parameters and subjective discomfort were monitored during the HTT.

Main Results:

• No significant physiological differences were observed between the sleep conditions during the HTT.
• Subjective discomfort was significantly higher following TSD compared to the well-rested and PSD conditions.
• Evening chronotypes exhibited higher body temperatures during the HTT after TSD compared to PSD (p = 0.017).
• Evening chronotypes showed higher temperatures than intermediate chronotypes during the initial hour of HTT after TSD (p < 0.05).

Conclusions:

• While physiological responses to heat may not differ significantly, total sleep deprivation increases subjective discomfort.
• Chronotype appears to influence thermoregulatory responses during exercise in heat following sleep deprivation, particularly in evening chronotypes.