Methods Subjects were 25 healthy young men (mean age, 23 years) who consented to
participate in a protocol approved by our institutional review board. Eligibility criteria
included bedtime between 11 PM and 1 AM, waking time between 7 and 9 AM, and time in
bed of 7.5 to 8.5 hours. None of the subjects had been immunized against influenza during
the preceding 3 years. Eleven subjects had their bedtime restricted to 4 hours (1-5 AM) for 6
nights and then extended to 12 hours per night for 7 nights to recover from sleep loss. 4 …