People with insomnia have difficulties falling asleep or staying asleep for more than a short time. Most adults need at least 8 hours of sleep every night to feel well rested. Not getting enough sleep for more than just a few days can cause serious health problems. - See more at: http://www.hcplive.com/publications/internal-medicine-world-report/2007/2007-05/2007-05_45#sthash.PppoR3dO.dpuf