Sleep hygiene. You need to get on a regular sleep schedule. To reset your sleep clock, go to bed at the same time every night, awaken at the same time every morning, don't nap during the day, use the bed for sleeping (not eating, TV watching, reading, etc), if you awaken during the night, stay in bed until your determined awakening time.
Keeping a routine. An elusive challenge for many, regular sleep can best be attained by having good sleep hygiene. Try to awaken and go to bed at same time even on weekends. Limit or decrease caffeine intake especially after 2pm. Most importantly stay physically and mentally active throughout the day. A few hours before bedtime, dim lights, limit tv/phone, keep conversations to minimum and room cool. .