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If you were to conduct a straw poll in your office, it may seem that most people need an extra cup of coffee in the morning because they slept too much, not because they slept too little. However, researchers from Brigham and Women's Hospital, Harvard Medical School and the Dana-Farber Cancer Institute have found that sleeping too much can be hazardous to your health as well. In a recent study, the team of researchers found that sleeping too much can raise a person's risk for colorectal cancer, the third-leading diagnosed cancer in the United States.

The study was based on data from two longitudinal studies, which means that they were administered over a number of years: the Health Professionals Follow-Up Study and the Nurse's Health Study. On a regular basis, both sets of participants in the study detail their demographics, lifestyle and any diseases and conditions they may have developed, including how often they sleep in a 24-hour period and whether they snore. In total, the study included 70,368 women and 30,121 men. At the start of the study, the men were 56 years old on average, while the women were 53 years old.

In total, the researchers documented 1,973 colorectal cancer cases over the course of the study. In people who slept over nine hours a night, they had up to double the risk of developing the cancer as people who slept seven hours a night.

However, researchers do not believe that a late night in is the culprit of the increased risk in colorectal cancer. In fact, they believe that people in the study spent more time in bed if they had sleep apnea, a  common symptom of which is loud snoring. Sleep apnea occurs when the airway is blocked partially or completely during sleep. Being overweight is a predisposing factor to the condition.

Because of the strenuous nature of sleep when a person has sleep apnea, sleep quality often suffers, meaning that the person needs to spent a greater amount of time in bed in order to receive the same amount of rest. Though little research has been performed on the link between sleep apnea and cancer, an animal study has found that the intermittent lack of oxygen in animals can cause tumors.

Experts acknowledge that everyone's sleep needs are different. Regardless, the golden standard, they say, tends to be about seven or eight hours a night.

The study was published in the journal Sleep.