Although personal needs vary, on average, adults need 7 to 8 hours of sleep per night. Babies typically sleep about 16 hours a day. Young children need at least 10 hours of sleep, while teenagers need at least 9 hours. To attain the maximum restorative benefits of sleep, getting a full night of quality sleep is important, says Twery.

Sleep can be disrupted by many things. Stimulants such as caffeine or certain medications can keep you up. Distractions such as electronics—especially the light from TVs, cell phones, tablets and e-readers—can prevent you from falling asleep.

As people get older, they may not get enough sleep because of illness, medications or sleep disorders. By some estimates, about 70 million Americans of all ages suffer from chronic sleep problems. The 2 most common sleep disorders are insomnia and sleep apnea.

People with insomnia have trouble falling or staying asleep. Anxiety about falling asleep often makes the condition worse. Most of us have occasional insomnia. But chronic insomnia—lasting at least 3 nights per week for more than a month—can trigger serious daytime problems such as exhaustion, irritability and difficulty concentrating.

Common therapies include relaxation and deep-breathing techniques. Sometimes medicine is prescribed. But consult a doctor before trying even over-the-counter sleep pills, as they may leave you feeling unrefreshed in the morning.