First-night effect on sleep time in dairy cows.

Area of Science:

• Animal behavior
• Sleep science
• Veterinary medicine

Background:

• The first-night effect, where sleep recordings differ on the first night due to environmental changes, is well-documented in humans.
• This phenomenon can alter sleep architecture, including rapid eye movement (REM) sleep duration and patterns.
• It is unknown if a similar first-night effect occurs in domestic animals like dairy cows.

Purpose of the Study:

• To investigate the presence and impact of a first-night effect on sleep and awake states in dairy cows.
• To analyze sleep architecture differences across three consecutive recording days in Swedish Red dairy cows.
• To determine if environmental novelty influences sleep patterns in this bovine population.

Main Methods:

• Non-invasive electrophysiological recordings were conducted on nine Swedish Red dairy cows over three consecutive 24-hour periods.
• Sleep and awake states, including REM sleep, non-REM (NREM) sleep, rumination, and drowsiness, were monitored and quantified.
• Statistical analyses were performed to compare sleep parameters between recording days and between diurnal/nocturnal periods.

Main Results:

• No significant differences were found in the total duration of awake, rumination, drowsiness, REM sleep, or NREM sleep between the three recording days.
• Bouts of REM sleep and rumination were significantly longer during nighttime compared to daytime, irrespective of the recording day.
• Awake bouts were shorter at nighttime than daytime, and awake bout duration showed an interaction effect, with longer daytime bouts on day 1 compared to day 3.

Conclusions:

• Dairy cows do not exhibit a significant first-night effect in terms of overall sleep and awake state durations.
• Circadian rhythms influence sleep architecture, with longer REM sleep and rumination bouts occurring at night.
• Further research is needed to fully understand the nuances of the first-night effect and sleep architecture in dairy cows.