Study: Lack of Sleep Negates Cognitive Benefits of Exercise in Middle-Aged People

Facts

• According to a UK study published Wednesday, adults over 50 who had higher levels of frequent and intense exercise while getting less than an average of six hours of sleep a night had a faster cognitive decline than those who got more sleep while exercising less frequently.¹
• The study's lead author, Dr. Mikaela Bloomberg of University College London, says their research suggests that sufficient sleep may be required to receive the "full cognitive benefits" of exercise.²
• The study tracked 9K British adults taking part in the English Longitudinal Study of Ageing over 10 years, with researchers cognitively testing and interviewing participants every two years. The results excluded adults with dementia or serious cognitive decline.¹
• Dr. Bloomberg explained that previous studies on sleep, exercise, and cognitive function only focused on particular moments of time, while this new, longitudinal research shows that exercise might not "counter the long-term effects" of sleep deprivation, something she says researchers were "surprised" by.³
• At the beginning of the study, those who exercised more had better cognitive function regardless of their sleep habits, while declines began in the physically active short sleepers by their 50s and 60s. For people aged 70 and over, exercise was found to benefit cognitive function regardless of sleep habits.²
• Study co-author Prof. Andrew Steptoe highlighted the need to identify more factors that may contribute to cognitive decline beyond physical activity, noting that the sleep hygiene of patients should be taken into consideration.²

Sources: ¹CNN, ²Guardian, and ³Scripps News.

Narratives

• Narrative A, as provided by Guardian. This study helps reaffirm what we know about sleep and cognitive function, as this woefully neglected aspect of our health gets the attention that it deserves. Sleep is a vital, restorative process that flushes out toxic proteins that accumulate in our brain throughout the day, a cleaning process that slows down as we age. Improving sleep quality in older adults could be a crucial piece of the puzzle when it comes to their cognitive health.
• Narrative B, as provided by New Scientist. While the plethora of studies surrounding cognitive decline and lifestyle seem promising, dementia is nonetheless an unpreventable condition, and media reporting on the matter may give people false hope about this frightening illness. Observational studies are less valuable than randomized trials, and an intractable chicken-or-the-egg problem emerges when studying lifestyle and cognitive function: do healthy habits reverse or prevent cognitive decline, or are people with cognitive decline less likely to have healthy habits?