• vigilance;
  • circadian rhythm;
  • neurobehavioral performance

OBJECTIVES: To determine whether healthy aging is associated with increased sleepiness and whether healthy older adults experience more sleepiness when acutely sleep deprived.

DESIGN: A 5-day inpatient circadian rhythm–sleep study consisting of 3 baseline nights followed by an extended 26-hour wake episode under constant conditions.

SETTING: Intensive Physiological Monitoring Unit, General Clinical Research Center, Brigham and Women's Hospital.

PARTICIPANTS: Thirty-seven healthy participants without medical, psychological, or sleep disorders: 26 young (7 women, 19 men; mean age 21.9±3.3, range 18–29) and 11 “young-old” adults (3 women, 8 men; mean age 68.1±3.6, range 65–76).

INTERVENTION: An extended 26-hour wake episode under constant conditions.

MEASUREMENTS: Electroencephalographic-verified wakefulness, slow eye movements, sustained attention, subjective sleepiness.

RESULTS: During the first 16 hours corresponding to the usual waking day, both groups rated themselves as alert and had similar levels of vigilance and little evidence of sleepiness. As the wake episode continued, the older subjects were less impaired, showing faster reaction times, fewer performance lapses and attentional failures, and less frequent unintentional sleep episodes than the younger subjects.

CONCLUSION: This small study suggests that excessive sleepiness is not normal in healthy older adults. Symptoms of excessive sleepiness in this population, including reliance on caffeine to maintain alertness, should be evaluated and treated. Further study is needed to determine whether daytime sleepiness in middle-old (75–84 years) and old-old (≥85) adults is normal or is instead associated with sleep restriction, undiagnosed sleep disorders, medication side effects, mood disorders, or other medical disorders that disrupt sleep.