In general, exercising regularly, avoiding overeating at night, and avoiding stressful activities and thoughts can help you improve sleep. Also, while your sleep cycle is generally 90 minutes long, the quality of your sleep can change depending on what times you are asleep.
The earlier in the night you sleep, the more likely you will experience deep non-REM sleep, and the later in the morning, the greater the chance of you experiencing REM sleep. Therefore, if you sleep in, you have a greater chance of enjoying a greater proportion of REM sleep.
For those with sleep apnea, losing excess weight, either on your own or with the help of a weight-loss program, can relieve throat constriction. In some cases, weight loss can cure sleep apnea. Check with your doctor though as untreated sleep apnea can have very serious consequences.
Sleeping on the side, instead of on your back, also helps with apnea. When you sleep on your back, your tongue and soft palate can hit the back of your throat and block your airway. To prevent sleeping on your back, you can sew a tennis ball in the back of your pajama top.
To keep your nasal passages open at night, you can use a saline spray. However, you should consult your doctor first about using nasal decongestants or antihistamines since these medications are generally not recommended for long-term use and are not treatments for sleep apnea.