Excessive daytime sleepiness is often a sign of sleep apnea, a disorder that causes interruptions in breathing during sleep up to several times per night. It may be caused by faulty signals from the brain or because the soft tissue at the back of the throat relaxes and blocks the airway (called obstructive sleep apnea, or OSA). Most people with sleep apnea don't know what is happening or why they feel so tired after what seems like a full night's rest. People with diabetes are more likely to have sleep apnea than people without diabetes — and OSA itself increases the risk of insulin resistance and may be a roadblock to diabetes control. If you have sleep apnea, or if you experience unusual sleepiness during the daytime, talk with your doctor. A full night's sleep is not just a luxury, it's a health necessity.