Five-hour sleep restriction for 7 days increases subjective sleepiness

Area of Science:

• Sleep Science
• Human Physiology
• Psychology

Background:

• Adequate sleep is crucial for cognitive function and well-being.
• Chronic sleep restriction is a common issue, particularly among students.
• Understanding the impact of partial sleep deprivation on subjective sleepiness is important.

Purpose of the Study:

• To investigate the effects of 7-day sleep restriction (5 hours/night) on subjective sleepiness.
• To compare sleepiness levels during sleep restriction with baseline (8 hours/night) conditions.
• To analyze the time-course of changes in subjective sleepiness during sleep restriction.

Main Methods:

• 13 healthy male students participated in a randomized crossover study.
• Two conditions: 7 days of 8-hour sleep (baseline) and 7 days of 5-hour sleep (restriction).
• Subjective sleepiness assessed using a Visual Analog Scale (VAS) every 3 hours (0900-2100) daily.

Main Results:

• Subjective sleepiness (VAS scores) gradually increased during the 5-hour sleep restriction, plateauing by day 5.
• Mean VAS scores during the last three days of sleep restriction were significantly higher than baseline (p<0.001).
• The daily pattern of sleepiness (peak at 0900, dip at 1200, increase towards 2100) was similar between conditions.

Conclusions:

• A 7-day, 5-hour sleep restriction significantly elevates subjective sleepiness in healthy young adults.
• Subjective sleepiness accumulates over the first five days of restriction before reaching a plateau.
• While overall sleepiness increases, the daily fluctuation pattern of sleepiness remains consistent with baseline sleep.