When the alarm goes off after a late-night, it's always a dilemma: Do you sacrifice a restful hour to force your body into a tired workout? You might be better off sleeping in and skipping your morning jog.
Experts say that in an ideal world you would both get enough sleep and exercise. A new study suggests exercise may help to counteract the negative health effects of inadequate sleep.
The new research builds on a body of work that shows how important sleep and fitness is for overall health. Multiple studies have shown that a healthy amount of sleep and fitness is linked with increased longevity. At least one study suggested that sleep issues increased the risk of a person dying during the follow-up phase, but regular exercise reduced that risk.
Researchers in China examined the data of over 92,000 adults aged between 40 and 73 in the United Kingdom to better understand exercise's protective effects. The participants wore a wristband for a week from 2013 to 2015 that tracked how much they slept and exercised. This was used by the researchers as an indicator of their lifestyle.
Researchers then followed up on the health of participants several years later. Those who had poor sleep or who slept excessively (which can be problematic in and of itself) and did not exercise were more likely to have died during this period. This included cancer and cardiovascular diseases. Researchers also found a surprising pattern in the data. People who exercised regularly did not face an increased mortality risk, even if they slept for less than six hour each night.
Jihui Zhang is the director of Affiliated Brain Hospital at Guangzhou Medical University and the author of the study. He says that the study shows that 150 minutes of vigorous or moderate physical activity per week could negate the negative health effects of sleeping too little or too much. He said that doing something was better than nothing. Regular short walks or rides in a stationary bicycle could be beneficial.
The study was purely observational, and did not prove that exercise can counteract the effects of poor sleep. Of course, a week's worth of data on sleep and exercise may not be representative of a person's entire life. The findings are intriguing and provide a new window on the health benefits associated with exercise.
Dr. Zhang explained that the researchers in the new study hypothesized that exercising could help counteract the effects of poor sleep, either by reducing inflammation or by regulating metabolism and sympathetic nervous activity. It is also possible that poor sleeping habits contribute to heart disease by increasing blood pressure and decreasing insulin resistance. Dr. Virend Virend, a cardiologist at Mayo Clinic who studies the effects of sleep loss, believes this. Exercise could counteract this by regulating the blood pressure and increasing insulin sensitivities.
Jennifer Heisz is an associate professor and author at McMaster university who wrote 'Move The Body, Heal The Mind'. She said that the brain is one of the most compelling places where exercise affects sleep. This is partly because a vigorous workout stimulates the production of a chemical known as adenosine. It acts as a sleep aid. She said that the more adenosine our bodies produce throughout the day, then the more restful, restorative sleep we get.
Tianyi Huang, assistant professor of medicine and sleep at Harvard Medical School, has studied heart health. He said that people who don't sleep enough are less likely to be active throughout the day. This is especially true if they have a busy work schedule. If you have trouble sleeping for long periods, you might want to speak to a sleep specialist or doctor. Research has shown that morning exercise may have a different effect on your body than evening workouts.
The study shows that people who are not able to manage their sleep well should schedule time for moderate or vigorous exercise, said Dr. Donald Lloyd-Jones. He is a former President of the American Heart Association, and chair of the Department of Preventive Medicine at Northwestern University’s Feinberg School of Medicine.
Dr. Somers explained that not everyone needs the same amount of sleep. Some people are able to function or feel rested enough with less hours. He said that it's possible some of the "short sleepers" in the study had already slept enough and were therefore more able than others to do a workout with no increased cardiovascular risk.
Aric Prather is a sleep specialist and psychologist at the University of California in San Francisco. He said that people who are sleep deprived may be more prone to injury during an exercise session. It's not a question of whether you should sacrifice sleep in favor of exercise. He said that people who are successful do both.