MIT Technology Review reports on causes and costs of sleeplessness, plus offers solutions.

If there’s a common thread woven through the experts’ advice on how to sleep well and wake up refreshed, it’s this: understand the power of light—especially in the morning.

A strong dose of light first thing in the morning can offset grogginess, Kushida says. Patients who give themselves about 30 minutes of light exposure shortly after waking are more likely to feel alert all day.

Meanwhile, there’s evidence that waking up gradually in response to light—as if dawn were illuminating the room naturally —is not only more pleasant, but yields benefits all day long. “The presence of light prior to awakening has been shown to increase our body’s level of cortisol, which is a neurohormone that helps to prepare our brain and body for the stressors of the day,” Decker explains. Extra light and cortisol in the morning allow people to adapt better to stress throughout the day, helping them deliver peak performance.