Def: temporary misalignment between body clock and destination solar/sleep-wake cycle
Typically after trans-meridian travel across ≥3 time zones
Direction of travel
Usually worse with eastward travel, needs phase advance
Phase advance harder to achieve than phase delay (westward)
80% of people have intrinsic circadian period >24 hrs, constantly delaying slightly
Makes eastward phase advance harder and slower
Clock typically resets ~1 hr/day eastward vs ~1.5 hrs/day westward
Severity factors
- Number of time zones crossed
- Sleep loss before and during travel
- Timing of light exposure at destination
Clinical features
Transient, sx start within 1-2 days after travel
Sleep disturbance
Reduced daytime alertness, fatigue
Somatic sx incl GI complaints
Management
Esp important in pts with comorbid sleep d/o
Short trips (<3-4 days): stay on origin time
Long eastward trips: phase advance, can start before travel and continue at destination
Long westward trips: phase delay, can start before travel
Timed light exposure and avoidance
± timed low-dose melatonin (0.5 mg)
Cochrane review supports melatonin for ≥5 time zones, esp eastward
- Oxford Handbook of Sleep Medicine 2022