Effects of temperature on sleep in the developing rat

Area of Science:

• Developmental Neuroscience
• Sleep Research
• Autonomic Physiology

Background:

• Autonomic system development is largely postnatal in altricial species like rats and humans.
• Immature autonomic functions are vulnerable to environmental factors, including ambient temperature (Ta).
• Ta influences adult sleep/wake states, and overheating is linked to sudden infant death syndrome.

Purpose of the Study:

• To investigate the impact of ambient temperature variations on sleep/wake state structure and sleep intensity in developing rats.
• To understand the relationship between thermoregulation and sleep during early postnatal development.

Main Methods:

• Neonatal Long-Evans hooded rats were surgically prepared for chronic sleep/wake state and brain temperature (Tbr) recording.
• Sleep/wake state and Tbr were recorded for two hours on postnatal days 12, 14, 16, 18, and 20.
• Recordings were conducted at three different ambient temperatures: 28.0-30.0°C, 33.0-35.0°C, and 38.0-40.0°C.

Main Results:

• Ambient temperature significantly affected the sleep/wake state structure in developing rats.
• Sleep intensity, measured by slow-wave activity during slow-wave sleep, showed minimal changes with varying Ta.
• Developing rats exhibited altered sleep architecture in response to different ambient temperatures.

Conclusions:

• Ambient temperature is a critical environmental factor influencing sleep/wake states during early postnatal development in rats.
• Sleep intensity appears to be relatively robust against ambient temperature fluctuations in developing rats.
• Findings contribute to understanding thermoregulatory influences on sleep ontogeny and potential vulnerabilities.