Overview
Specific Aims
Importance
Background
Lipids
Diet
Phy. Act.
Body Mass
S.A.D.
CHD
B.P.
Stroke
Prelim. Studies

Methods
Study Design
Protocol
Data Collection
Analysis

Data
Introduction
Basic Data Sets
Variables Defs.
Codebook

Results
Working Papers
Publications
References

Seasonal variation of a variety of behaviors has been extensively documented in animals,(13) but seasonal effects in humans have been less well studied. Research utilizing population data has suggested that there are seasonal rhythms in human birth rates, suicide, and mortality (14). Of particular interest are apparent seasonal rhythms in cardiovascular morbidity and mortality, (15) primarily sudden death and stroke (16, 17). These variations have been related to changes in temperature (18, 19), exposure to daylight (20), and various other mechanisms that lead to changes in blood coagulability (21). Seasonal affective disorder (SAD), involving a marked winter-time increase in self-reported depression, weight, and appetite, has received considerable recent attention, highlighting the importance of seasonal rhythms in human behavior (22). Spoont and colleagues have reported that variations in mood due to changes in seasons occur in the entire population, with SAD patients only representing the extreme right tail of the distribution (23).