Why is it so hard for me to get up in the morning?

If you have a delayed sleep phase and you tried to wake up at a "normal" time this morning, such as 7:30 am, there are two reasons you probably found it difficult and unpleasant. First you didn't spent enough time sleeping to fulfill your sleep requirement. The other reason is that the drive for sleep follows a cycle, determined by the biological clock. The middle of the night, or shortly after, is when the drive for sleep is greatest - and if you have a tendency to fall asleep at 3 or 4 am and get up around noon, 7:30 am is close to the middle of the night for you.

The variation in "drive for sleep" at different times of the day is physiologic, not just a matter of habit or choice. There are several other rhythms in the body which are closely related to sleep/wake patterns. For example, body temperature rises and falls during the day. You tend to fall asleep when your body temperature is falling; it reaches a minimum around the middle of the night (meaning, again, the individual's subjective night) and then rises again toward morning. The concentration of melatonin in the blood rises during the evening, peaks during the night, and then decreases again. Hunger to some extent also follows circadian rhythms - if you get up too early you likely don't feel like eating breakfast right away. Loosely speaking, when the biological clock says it is time to be asleep, the body gears down in many ways, and during that time it is hard to wake up or to be fully alert.

Besides DSPS, there are many other causes of difficulty waking up and daytime sleepiness. Some of the more common ones are listed below.

• The most common cause of daytime sleepiness and difficulty awakening, at all ages, is simply insufficient sleep. Teenagers often don't get enough sleep - many adolescents need 9 or 10 hours of sleep every night and some need more.
• Sleep apnea is a very common, treatable disorder in which breathing is disrupted during sleep. Symptoms of sleep apnea include snoring, waking up with a headache, and waking up during the night. Self-scoring quiz: could you have sleep apnea?; Sleep Apnea FAQ
• Narcolepsy is another cause of chronic daytime sleepiness. The symptoms of narcolepsy often emerge during adolescence and include cataplexy (temporary loss of muscle control following strong emotion), sleep paralysis (temporary inability to move while falling asleep or waking up), waking up during the night, and hallucinations while falling asleep. Excessive daytime sleepiness, with a strong need to nap often, is usually the first symptom to develop.
• Some individuals, particularly children and adolescents, deal with depression by sleeping a lot more than they actually need to.
• Illness, particularly viral infections, can cause fatigue and sleepiness which disappear soon after the disease has run its course.
• Periodic Limb Movements are movements of the arms and legs during sleep
• Individuals with hypersomnia have difficulty awakening and persistent daytime sleepiness. Neither going to sleep earlier nor waking up later relieves the symptoms even though their nighttime sleep is technically normal. They do not have difficulty falling asleep at night. Like insomnia, hypersomnia has a variety of causes.
• Seasonal Affective Disorder (SAD) causes sleepiness, and depression that can be severe and lead to suicide. Other symptoms of SAD are craving for sweets and carbohydrates, and weight gain. The symptoms of SAD appear only in the fall and winter, and disappear in the spring.

In DSPS and other circadian rhythm sleep disorders, daytime sleepiness is greatly reduced when the individual's preferred sleep/wake times are followed. Have you ever been able to wake up as late as you wanted to for more than a few days at a time? If you still often felt sleepy during the day, it is likely that something other than DSPS is contributing to your sleepiness. Excessive daytime sleepiness is usually treatable, and should be investigated by a professional trained in diagnosing and treating sleep disorders.

Pulmonary Diagnostics and Consulting Sleep Questionnaire