Napping, nighttime sleep, and cardiovascular risk factors in mid-life adults.
OBJECTIVE
To evaluate the relations between sleep characteristics and cardiovascular risk factors and napping behavior, and to assess whether daytime napping leads to subsequent better or worse sleep.


METHODS
The sample consisted of 224 (African American, Caucasian, and Asian) middle-aged men and women. Sleep measures included nine nights of actigraphy and sleep diaries, sleep questionnaires, and one night of polysomnography to measure sleep disordered breathing.


RESULTS
More frequent napping was associated with shorter nighttime sleep duration averaged across the nine nights of actigraphy (especially among African Americans), more daytime sleepiness, more pain and fatigue by diary, and increased body mass index and waist circumference. Shorter nighttime sleep duration was associated with taking a nap during the next day and taking a nap was associated with less efficient sleep the next night.


CONCLUSIONS
Napping in middle-aged men and women is associated with overall less nighttime sleep in African Americans and lower sleep efficiency as measured by actigraphy, and increased BMI and central adiposity. These findings point to the importance of measuring of napping in understanding associations of sleep with cardiovascular risk.
Owens
Jane F
JF
Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA. owensjf@upmc.edu
Buysse
Daniel J
DJ
Hall
Martica
M
Kamarck
Thomas W
TW
Lee
Laisze
L
Strollo
Patrick J
PJ
Reis
Steven E
SE
Matthews
Karen A
KA
D000368:Aged; D044383:Black People; D001794:Blood Pressure; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology*; D002940:Circadian Rhythm; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania; D017286:Polysomnography; D011446:Prospective Studies; D012307:Risk Factors; D012890:Sleep; D012892:Sleep Deprivation / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology*; D055105:Waist Circumference; D044465:White People; D001741:Black or African American