This study will investigate how sleep and mood are related in patients with depression and in healthy controls. It will use MRI-based measures of brain function to determine how neural systems are modulated by sleep and sleep deprivation, and its links to mood in depression.

The purpose of this work is to identify brain networks that underlie sleep and mood using a combination of EEG and fMRI. Sleep deprivation can elicit rapid improvements in mood in some patients with depression, while some patients do not show any significant changes in mood. We will image the brain while measuring physiological and electrical signals in healthy individuals and in patients with depression. Subjects will participate in combined EEG-MRI studies that will involve the use of perceptual and attentional tasks, and will involve recording physiological variables such as breathing, heart rate, eye movements, and blood pressure. If combined EEG-MRI cannot be completed due to data quality reasons, subjects will participate in EEG or MRI alone. Subjects will participate in a blood draw to assess for inflammatory markers related to mood. Subjects will be either well-rested or sleep deprived. For sleep deprivation, subjects will be asked to stay awake overnight under the supervision of a member of the study team at Boston University, and then would be asked to do an fMRI, EEG, or EEG-MRI scan. fMRI studies will be performed at the Boston University Center for Cognitive Neuroimaging. During the study visit, subjects will answer questions in structured interviews, will fill out questionnaires that will contain questions related to their mental health. Subjects will be shown visual stimuli and/or listen to auditory stimuli, and/or asked to perform simple behavioral tasks related to these stimuli. Some of the visual stimuli will be emotionally salient. Wrist actigraphy will be used to monitor sleep behavior. Remote daily mood and sleep assessments will be performed for up to two weeks prior to imaging. These assessments will be sent as emails or text messages to participants.

Inclusion criteria:

• Adult aged 18-80

Inclusion criteria for patient cohort only:

- Current diagnosis of major depressive disorder

Exclusion criteria:

• Must not have ferrous metal implanted in head or body
• Must have no history of major head trauma
• Must not have implanted electronic devices (e.g., pacemaker, neurostimulator)
• Must not be pregnant, suspect they are pregnant, or seeking to become pregnant
• Must not be claustrophobic
• Must have no piercings or jewelry that cannot be removed
• Weight less than 250 pounds
• No lifetime history of schizophrenia or any other psychosis disorder, substantial intellectual disability, bipolar disorder, post-traumatic stress disorder or obsessive compulsive disorder
• No alcohol or substance abuse or dependence within the past 6 months
• No significant personality dysfunction
• Must not indicate significant suicide risk.
• Must not be taking medications that significantly affect sleep, psychiatric function, blood/vascular function, or anti-inflammatory medications (other than minor NSAID use).