Funding stopped

1. To determine the effects of tDCS on subjective measures of sleepiness in night-shift workers with shift work disorder.
2. To determine the effects of transcranial direct current stimulation (tDCS) on vigilance in night-shift workers with shift work disorder.

This is a preliminary single-arm study. The study will last up to 6 weeks including the screening period. Subjects will receive active tDCS for 30 minutes before their scheduled work hours at least 3x/week for two consecutive weeks.

Outcome measures will include: psychomotor vigilance test (PVT) and the Karolinska Sleepiness Scale (KSS)25,26 which will be obtained during the shift work.

Inclusion Criteria:

• age 18-65 years

• works 5 or more night shifts per month (each shift lasting at least 10 hours, with ≥6 hours worked between 10 pm and 8 am) with plans to maintain this schedule for the duration of the 3-week trial

• meets the criteria for Shift Work Disorder according to the International Classification of Sleep Disorders24 and evaluation of a sleep medicine provider (physician or nurse practitioner) during a screening evaluation:

  1. affirmative answers to Do you experience excessive sleepiness? (yes/no); "Do you experience difficulties with falling asleep during opportunities for sleep? (yes/no); "Is the sleep or sleepiness problem related to a work schedule where you have to work when you would normally sleep? (yes/no)"; and "Has this sleep or sleepiness problem related to your work schedule persisted for at least three months? (yes/no)
  2. based on the evaluation of the sleep medicine provider, the sleep and/or wake disturbance are not better explained by another current sleep disorder, medical or neurologic disorder, mental disorder, medication use, poor sleep hygiene, or substance abuse disorder.

• Stable medication dosage over previous 4 weeks.

• Able to understand English and give a written informed consent document.

Exclusion Criteria:

• Currently taking stimulant medications such as Modafinil, Armodafinil, Methylphenidate, or Dextroamphetamine.
• History of automobile accident due to falling asleep while driving
• Inability to understand or read English
• Self-reported Substance abuse (current)
• Excessive alcohol consumption defined as:
• More than 3 glasses of wine a day
• More than 3 beers a day
• More than 60 mL of hard liquor a day
• Presence of cardiac pacemaker or automatic implantable cardioverter-defibrillator (AICD).
• Pregnancy, lactation (will be screened with urine pregnancy test)
• Non-removable metal or tattoos around head
• Use of implantable birth control device such as Implanon
• History of frequent severe headaches
• Unstable coronary artery disease
• Uncontrolled Seizure disorder
• Uncontrolled hypertension
• Any other clinically significant condition that, in the opinion of the Investigator, might put the subject at risk of harm during the study or might adversely affect the interpretation of the study data.

Adverse events were assessed through study completion (6 weeks for each participant).

No adverse events were observed or reported during the study.

Outcome measurements and adverse events were not analyzed and reported as the study was terminated due to funding stopped