The effects of sleep deprivation are often difficult to study because they are often confounded by

The answer is: Insomnia.

Explanation:

Lack of sleep should not be confused with Insomnia. Sleep deprivation is the condition of insufficient sleep and may be chronic or acute. Few studies have compared the effects of acute total lack of sleep and partial chronic lack of sleep, which are often preceded by periods of insomnia.

The answer is: Insomnia.

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