Two different studies presented Wednesday at the annual meeting of the American Academy of Sleep Medicine suggest the following: most seniors aren’t sleeping well, and sleep deprivation doesn’t affect cognitive performance.

The first study, from the University of Virginia, indicates that the majority of seniors—55%—do not get the recommended eight hours of sleep per night. Those who exhibited depressive symptoms and poor mental health most commonly reported lack of sleep, according to study authors. Researchers were surprised to discover that self-reported levels of physical activity did not seem to have any connection to how much sleep seniors get. They also noted that lack of sleep was not a predictor of functional ability as a result of feeling tired during the day.

A separate study found that seniors’ cognitive performance is less affected by sleep deprivation than younger adults. Researchers kept a group of seniors aged 59 to 82 and a group of young adults aged 19 to 38 awake for 36 straight hours, and then subjected them to a barrage of cognitive tests. The older group out-performed the younger cohort on a wide variety of mental acuity tests, including measures of working memory, selective attention/inhibition and verbal encoding and retrieval. The researchers at the University of California, San Diego, noted, however, that only very healthy seniors took part in the study, and that no such considerations were made for the younger group.

Both studies were presented Wednesday at the annual SLEEP meeting, held this year in Seattle, WA. The SLEEP meeting gathers researchers from across the country, and is hosted by the American Academy of Sleep Medicine and the Sleep Research Society.