The Sleep Lengthening and Metabolic Health, Body Composition, Energy Balance and Cardiovascular Risk Study

Research Questions

• Is it feasible to improve sleep duration and quality in habitually short sleepers under free-living conditions?
• What are the effects of improved sleep duration and quality on body composition, energy balance, dietary intake, and cardio-metabolic risk factors?

Hypothesis

• Improved sleep duration and/or quality in habitually short sleepers will result in improved energy balance, diet quality, body composition, and cardio-metabolic risk profile.

Aims

• To assess the feasibility of improving sleep duration and/or quality in habitually short sleepers using behavioural approaches and public health messages targeting sleep hygiene.
• To identify how improved sleep duration and/or quality affect energy balance, diet quality, body composition, and cardio-metabolic risk profile.

Objectives

• To develop a sleep extension strategy using behaviour change techniques (BCTs) targeting sleep hygiene.
• To recruit healthy adults who are habitually short sleepers and randomise eligible participants to an intervention and control group.
• To assess the feasibility and effectiveness of the intervention.
• To measure energy balance, diet quality, body composition and cardio-metabolic risk factors pre- and post-treatment in the intervention and control groups.
• To assess whether the intervention had an effect on the aforementioned parameters by comparing the intervention endpoints to control as well as baseline measures.
• To run the statistical analysis both on an intention-to-treat basis as well as per-protocol.

Inclusion criteria

• Healthy male and female adults (18-64 years)
• Habitually short sleepers (5-<7 hours of sleep per night on average on weekdays) - this is self-reported at screening, and confirmed by actigraphy when baseline measurement is taken.
• BMI: 18.5 - <30

Exclusion criteria

• Diagnosed medical conditions such as:
• Cardiovascular disease
• Type 1 or Type 2 Diabetes Mellitus
• Cancer (excluding basal carcinoma) in the past five years
• Chronic renal or liver disease
• Inflammatory bowel disease
• Hypo/hyperthyroidism
• Sleep conditions:
• Chronic use of sleeping aid medication
• Insomnia (Insomnia Severity Index - ISI Questionnaire)
• Sleep apnoea (Berlin Questionnaire)
• Extreme Chronotype (HorneOstberg questionnaire)
• Pregnancy or lactation
• Weight change of >3 kg in the previous two months
• Previous or current high alcohol intake (>28 units/week for males and >21 units/week for females) or substance abuse
• Smoking
• Working hours outside 7 am - 7 pm
• Habitual napping (>20 minutes per day on a regular basis)
• Obliged to wake and care for family/friends (e.g. new born child etc)
• Use of antidepressants
• Depressed mood (Center of Epidemiologic Studies of Depression 20-item scale questionnaire)
• Travel arrangements outside time zone within the periods of data collection
• Travel arrangements outside time zone within period of intervention/control condition
• Inability to adhere to a sleep hygiene intervention/sleep schedule due to time commitments