Nocturnal hypoglycemia is a drop in blood sugar levels while a patient is sleeping. It is most commonly seen in patients with diabetes, and can pose serious health risks if it is not managed appropriately. One problem with hypoglycemia in general is a phenomenon called hypoglycemia unawareness, where people may not realize they have dangerously low blood sugar because the symptoms are often subtle, and this can be an especially big problem with drops at night, when patients aren't awake to take note of even slight physical changes.

In patients who need insulin therapy, nocturnal hypoglycemia can be a reflection of the need to change the dosage or switch medications. It can also happen when people do not eat a snack before bed, don't monitor their levels enough, or exercise heavily before bed and fail to make up for it with additional nutrition. Patients with nocturnal hypoglycemia will experience night sweats and can wake up with a headache and a feeling of being generally run down. Their blood sugar levels in the morning may also be very low.

A risk with drops in blood sugar overnight is the development of convulsions or, in extreme cases, coma. In addition, cardiac arrhythmias can appear in patients with low blood sugar, and these may be life threatening. Over time, permanent damage to the patient's organs may occur because of the fluctuating blood sugar levels, and patients can develop complications of diabetes, like neuropathy, where the peripheral nervous system is damaged and impaired sensation, numbness, and tingling occur.

There are several ways patients can approach management of nocturnal hypoglycemia. Monitoring blood sugar levels more closely and adjusting insulin injections may help, as can switching drugs to get longer-acting medications to keep blood glucose levels more stable. Patients not in the habit of snacking before bed should start, and it may be necessary to adjust the timing of an exercise program to avoid creating a blood sugar crash during the night. Waking up to check blood glucose around three in the morning may be recommended in some cases.

Partners of people with diabetes should be alert to the signs of nocturnal hypoglycemia, as the patient may not notice. If someone starts sweating a lot at night, develops labored breathing, seems unusually sluggish in the morning, or experiences convulsions during sleep, a trip to the doctor is in order to find out more. Catching this problem early can head off long term damage and improve quality of life for the patient significantly.