You may qualify for this study if you meet the following criteria.

Inclusion Criteria:

• Female
• 18-35 years old
• Generally healthy
• Regular sleep patterns (7-9 hours per night, bedtimes between 9pm-2am)
• Regular menstrual cycle with duration of 26-35 days
• Willing to abstain from drugs (including caffeine, nicotine, and alcohol) for the entire duration of the study

Exclusion Criteria:

• Currently using hormonal birth control, or any hormonal/fertility medication in the past
  3 months
• Any diagnosis of sleep disorders
• Currently pregnant or breastfeeding
• ADHD or autism spectrum disorder
• History of psychiatric illness (personal or immediate family)
• History of treatment with antidepressant, neuroleptic medications, or major tranquilizers
• Currently on any other prescription medications (limited use of inhaler is okay)
• Current diagnosis of any other cardiovascular, respiratory, infectious, gastrointestinal, immunological, hematopoietic, neoplastic, endocrinologic, metabolic, neurologic, or female reproductive disease or disorder

Participation involves 4 screening visits, one 11–day inpatient stay, and additional tasks to complete on your own. 

Screening: 

The first screening visit is expected to take 3-4 hours. At this visit, we will ask about your medical history and ask you to complete several questionnaires about your personality, mental health, and quality of life. This visit may take place at our office at Brigham and Women’s Hospital or may be done virtually. 

The second screening visit is a virtual interview with our study psychologist, which is expected to take 1 hour. 

The third screening visit is a physical exam, during which you will meet with a doctor and we will also draw blood, take a urine sample, do an electrocardiogram (EKG). This visit is expected to take 1.5-2 hours. 

The fourth screening visit, which is expected to take 1-1.5 hours, involves a meeting (either virtual or in–person) with one of our study investigators to discuss the inpatient part of the study. 

Before the inpatient stay: 

For at least 3 weeks prior to the inpatient study, we will ask you to keep a consistent sleep- wake schedule in which we expect you to be in bed and sleeping for 8-10 hours per night at the same time every night. We will ask you to keep a log of when you go to bed and when you wake up. You will also need to call into our voicemail system every time you go to sleep and every time you wake up. We will also ask you to wear an actigraph device on your wrist for at least one week before the inpatient study. We will also ask you to track your menstrual cycle. 

Inpatient stay: 

During the 11–day inpatient study, we will ask you to live in our laboratory for 11 days in a room with no windows, clocks, phone, or internet. You will not be able to have outside 

visitors. We will tell you when you can sleep and when you need to stay awake. You may get less sleep than you get at home. We will plan all your meals and serve them to you at times we decide. We will take blood samples multiple times through an IV that is inserted into your arm. We will record your sleep using electrodes attached to your scalp and chest. We will collect saliva and urine samples from you. We will collect your body temperature continuously using a rectal sensor. We will ask you to take multiple tests on the computer. We may also periodically test you for COVID–19. 

After the inpatient stay: 

After the 11–day inpatient study, we will ask you to complete a daily sleep log until the next time you get your period.