We all know that diet and physical activity are essential to good health, but many are unaware that getting adequate sleep is equally important, if not more so. Sleep affects everything from energy and appetite to performance, mood, attention, memory, and decision making. It is the time when the brain forms and maintains the pathways that let us learn and create new memories. Recent research suggests that the body uses sleep time to remove toxins and metabolic “trash” from the brain (possibly including the plaques that contribute to Alzheimer’s disease). Habitual short sleep duration is associated with greater risk of obesity, high blood pressure, diabetes, depression, and cardiovascular disease. Unfortunately, about one third of U.S. adults get less than the recommended seven hours of sleep a night.
“While we don’t understand everything about sleep, we know it is essential for life,” says Jos Ordovs, PhD, a professor at the Friedman School and director of the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging. “We can survive extended periods of time without eating but we cannot go for very long without sleeping.”
How Sleep Works: When we’ve been awake for a long time, we begin to get sleepy; our bodies then try to maintain sleep long enough that we wake up restored and rested. This process is controlled by an internal biological mechanism called sleep/wake homeostasis. Medical conditions, medications (including some for high blood pressure and asthma), stress, sleep environment, and even what we eat and drink can influence sleep-wake needs. Exposure to light is especially critical. Our circadian rhythms respond to light and darkness, releasing hormones to help us feel awake (like cortisol and adrenaline) or promote sleep (like melatonin and GABA). This internal ‘biological clock’ works with sleep/wake homeostasis to regulate the timing of periods of sleepiness and wakefulness throughout the day. If you tend to get sleepy in the afternoon no matter how much sleep you’ve gotten (or feel great early in the morning despite not getting much sleep), that’s your circadian rhythms at work. Traveling between time zones disrupts circadian rhythms, and so does keeping long and irregular hours.