Delayed sleep phase disorder (DSPD), inability to awaken and fall asleep at socially acceptable times but no problem with sleep maintenance, a disorder of circadian rhythms. Other such disorders are advanced sleep phase disorder (ASPD), non-24-hour sleep–wake disorder (non-24) in the sighted or in the blind, and irregular sleep wake rhythm, all much less common than DSPD, as well as the situational shift work sleep disorder.
Stay cool at night. Make sure your bedroom is at the right temperature to help ensure a good night’s sleep. The National Sleep Foundation suggests setting the temperature between 60 and 67 degrees Fahrenheit for optimal sleep. Using cooling sheets and pillows can also help, especially for women in menopause who are experiencing hot flashes at night, says Dr. Alyssa Dweck, assistant clinical professor of obstetrics and gynecology at the Mount Sinai School of Medicine and co-author of “V is for Vagina.”